--- loncom/homework/grades.pm	2009/06/06 19:36:37	1.574.2.2
+++ loncom/homework/grades.pm	2010/04/01 01:00:28	1.574.2.9
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # The LON-CAPA Grading handler
 #
-# $Id: grades.pm,v 1.574.2.2 2009/06/06 19:36:37 raeburn Exp $
+# $Id: grades.pm,v 1.574.2.9 2010/04/01 01:00:28 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -97,9 +97,15 @@ sub ssi_print_error {
 #
 # --- Retrieve the parts from the metadata file.---
 sub getpartlist {
-    my ($symb) = @_;
+    my ($symb,$errorref) = @_;
 
     my $navmap   = Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        if (ref($errorref)) { 
+            $$errorref = 'navmap';
+            return;
+        }
+    }
     my $res      = $navmap->getBySymb($symb);
     my $partlist = $res->parts();
     my $url      = $res->src();
@@ -144,9 +150,15 @@ sub nameUserString {
 #--- Get the partlist and the response type for a given problem. ---
 #--- Indicate if a response type is coded handgraded or not. ---
 sub response_type {
-    my ($symb) = shift;
+    my ($symb,$response_error) = @_;
 
     my $navmap = Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        if (ref($response_error)) {
+            $$response_error = 1;
+        }
+        return;
+    }
     my $res = $navmap->getBySymb($symb);
     my $partlist = $res->parts();
     my %vPart = 
@@ -193,12 +205,17 @@ sub get_display_part {
 #--- Show resource title
 #--- and parts and response type
 sub showResourceInfo {
-    my ($symb,$probTitle,$checkboxes) = @_;
+    my ($symb,$probTitle,$checkboxes,$res_error) = @_;
     my $col=3;
     if ($checkboxes) { $col=4; }
     my $result = '<h3>'.&mt('Current Resource').': '.$probTitle.'</h3>'."\n";
+    my ($partlist,$handgrade,$responseType) = &response_type($symb,$res_error);
+    if (ref($res_error)) {
+        if ($$res_error) {
+            return;
+        }
+    }
     $result .='<table border="0">';
-    my ($partlist,$handgrade,$responseType) = &response_type($symb);
     my %resptype = ();
     my $hdgrade='no';
     my %partsseen;
@@ -766,7 +783,13 @@ sub verifyreceipt {
     if ($env{"course.$courseid.receiptalg"} eq 'receipt2' ||
 	$env{"course.$courseid.receiptalg"} eq 'receipt3') { $receiptparts=1; }
     my $parts=['0'];
-    if ($receiptparts) { ($parts)=&response_type($symb); }
+    if ($receiptparts) {
+        my $res_error; 
+        ($parts)=&response_type($symb,\$res_error);
+        if ($res_error) {
+            return &navmap_errormsg();
+        } 
+    }
     
     my $header = 
 	&Apache::loncommon::start_data_table().
@@ -1731,11 +1754,8 @@ sub gradeBox {
     }
     $line.='<option value="reset status">'.&mt('reset status').'</option></select>'."\n";
 
-
-	#&mt('<td><b>Part:</b></td><td>[_1]</td><td><b>Points:</b></td><td>[_2]</td><td>or</td><td>[_3]</td>',$display_part,$radio,$line);
     $result .= 
-	    '<td><b>'.&mt('Part').':</b></td><td>'.$display_part.'</td><td><b>'.&mt('Points').':</b></td><td>'.$radio.'</td><td>'.&mt('or').'</td><td>'.$line.'</td>'.
-    
+	    '<td><b>'.&mt('Part').':</b></td><td>'.$display_part.'</td><td><b>'.&mt('Points').':</b></td><td>'.$radio.'</td><td>'.&mt('or').'</td><td>'.$line.'</td>';
     $result.='</tr></table>'."\n";
     $result.='<input type="hidden" name="stores'.$counter.'_'.$partid.'" value="" />'."\n".
 	'<input type="hidden" name="oldpts'.$counter.'_'.$partid.'" value="'.$score.'" />'."\n".
@@ -1745,15 +1765,19 @@ sub gradeBox {
         $$record{'resource.'.$partid.'.tries'}.'" />'."\n".
         '<input type="hidden" name="aggtries'.$counter.'_'.$partid.'" value="'.
         $aggtries.'" />'."\n";
-    $result.=&handback_box($symb,$uname,$udom,$counter,$partid,$record);
+    my $res_error;
+    $result.=&handback_box($symb,$uname,$udom,$counter,$partid,$record,\$res_error);
+    if ($res_error) {
+        return &navmap_errormsg();
+    }
     return $result;
 }
 
 sub handback_box {
-    my ($symb,$uname,$udom,$counter,$partid,$record) = @_;
-    my ($partlist,$handgrade,$responseType) = &response_type($symb);
+    my ($symb,$uname,$udom,$counter,$partid,$record,$res_error) = @_;
+    my ($partlist,$handgrade,$responseType) = &response_type($symb,$res_error);
     my (@respids);
-     my @part_response_id = &flatten_responseType($responseType);
+    my @part_response_id = &flatten_responseType($responseType);
     foreach my $part_response_id (@part_response_id) {
     	my ($part,$resp) = @{ $part_response_id };
         if ($part eq $partid) {
@@ -2046,7 +2070,12 @@ KEYWORDS
     }
 
     my %record = &Apache::lonnet::restore($symb,$env{'request.course.id'},$udom,$uname);
-    my ($partlist,$handgrade,$responseType) = &response_type($symb);
+    my $res_error;
+    my ($partlist,$handgrade,$responseType) = &response_type($symb,\$res_error);
+    if ($res_error) {
+        $request->print(&navmap_errormsg());
+        return;
+    }
 
     # Display student info
     $request->print(($counter == 0 ? '' : '<br />'));
@@ -2593,7 +2622,12 @@ sub processHandGrade {
     }
     $ctr = 0;
     @parsedlist = reverse @parsedlist if ($button eq 'Previous');
-    my ($partlist) = &response_type($symb);
+    my $res_error;
+    my ($partlist) = &response_type($symb,\$res_error);
+    if ($res_error) {
+        $request->print(&navmap_errormsg());
+        return;
+    }
     foreach my $student (@parsedlist) {
 	my $submitonly=$env{'form.submitonly'};
 	my ($uname,$udom) = split(/:/,$student);
@@ -2791,8 +2825,12 @@ sub check_and_remove_from_queue {
 sub handback_files {
     my ($request,$symb,$stuname,$domain,$newflg,$new_part,$newrecord) = @_;
     my $portfolio_root = '/userfiles/portfolio';
-    my ($partlist,$handgrade,$responseType) = &response_type($symb);
-
+    my $res_error;
+    my ($partlist,$handgrade,$responseType) = &response_type($symb,\$res_error);
+    if ($res_error) {
+        $request->print('<br />'.&navmap_errormsg().'<br />');
+        return;
+    }
     my @part_response_id = &flatten_responseType($responseType);
     foreach my $part_response_id (@part_response_id) {
     	my ($part_id,$resp_id) = @{ $part_response_id };
@@ -3250,7 +3288,11 @@ sub viewgrades {
     $result.= '<h3>'.$common_header.'</h3>'.&Apache::loncommon::start_data_table();
     #radio buttons/text box for assigning points for a section or class.
     #handles different parts of a problem
-    my ($partlist,$handgrade,$responseType) = &response_type($symb);
+    my $res_error;
+    my ($partlist,$handgrade,$responseType) = &response_type($symb,\$res_error);
+    if ($res_error) {
+        return &navmap_errormsg();
+    }
     my %weight = ();
     my $ctsparts = 0;
     my %seen = ();
@@ -3310,7 +3352,11 @@ sub viewgrades {
 	      &Apache::loncommon::start_data_table_header_row().
 	      '<th>'.&mt('No.').'</th>'.
 	      '<th>'.&nameUserString('header')."</th>\n";
-    my (@parts) = sort(&getpartlist($symb));
+    my $partserror;
+    my (@parts) = sort(&getpartlist($symb,\$partserror));
+    if ($partserror) {
+        return &navmap_errormsg();
+    }
     my (undef,undef,$url)=&Apache::lonnet::decode_symb($symb);
     my @partids = ();
     foreach my $part (@parts) {
@@ -3469,7 +3515,11 @@ sub editgrades {
     my %columns = ();
     my ($i,$ctr,$count,$rec_update) = (0,0,0,0);
 
-    my (@parts) = sort(&getpartlist($symb));
+    my $partserror;
+    my (@parts) = sort(&getpartlist($symb,\$partserror));
+    if ($partserror) {
+        return &navmap_errormsg();
+    }
     my $header;
     while ($ctr < $env{'form.totalparts'}) {
 	my $partid = $env{'form.partid_'.$ctr};
@@ -3802,7 +3852,14 @@ ENDPICK
 
 sub csvupload_fields {
     my ($symb) = @_;
-    my (@parts) = &getpartlist($symb);
+    my ($symb,$errorref) = @_;
+    my (@parts) = &getpartlist($symb,$errorref);
+    if (ref($errorref)) {
+        if ($$errorref) {
+            return;
+        }
+    }
+
     my @fields=(['ID','Student/Employee ID'],
 		['username','Student Username'],
 		['domain','Student Domain']);
@@ -3902,8 +3959,12 @@ sub csvuploadmap {
     &csvuploadmap_header($request,$symb,$datatoken,$#records+1);
     my ($i,$keyfields);
     if (@records) {
-	my @fields=&csvupload_fields($symb);
-
+        my $fieldserror;
+        my @fields=&csvupload_fields($symb,\$fieldserror);
+        if ($fieldserror) {
+            $request->print(&navmap_errormsg());
+            return;
+        }
 	if ($env{'form.upfile_associate'} eq 'reverse') {	
 	    &Apache::loncommon::csv_print_samples($request,\@records);
 	    $i=&Apache::loncommon::csv_print_select_table($request,\@records,
@@ -4139,7 +4200,12 @@ LISTJAVASCRIPT
 	&mt('Manual Grading by Page or Sequence').'</span></h3>';
 
     $result.='<form action="/adm/grades" method="post" name="displayPage">'."\n";
-    my ($titles,$symbx) = &getSymbMap();
+    my $map_error;
+    my ($titles,$symbx) = &getSymbMap($map_error);
+    if ($map_error) {
+        $request->print(&navmap_errormsg());
+        return;
+    }
     my ($curpage) =&Apache::lonnet::decode_symb($symb); 
 #    my ($curpage,$mapId) =&Apache::lonnet::decode_symb($symb); 
 #    my $type=($curpage =~ /\.(page|sequence)/);
@@ -4234,8 +4300,14 @@ LISTJAVASCRIPT
 }
 
 sub getSymbMap {
+    my ($map_error) = @_;
     my $navmap = Apache::lonnavmaps::navmap->new();
-
+    unless (ref($navmap)) {
+        if (ref($map_error)) {
+            $$map_error = 'navmap';
+        }
+        return;
+    }
     my %symbx = ();
     my @titles = ();
     my $minder = 0;
@@ -4294,6 +4366,11 @@ sub displayPage {
     $request->print($result);
 
     my $navmap = Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        $request->print(&navmap_errormsg());
+        $request->print(&show_grading_menu_form($symb));
+        return;
+    }
     my ($mapUrl, $id, $resUrl)=&Apache::lonnet::decode_symb($env{'form.page'});
     my $map = $navmap->getResourceByUrl($resUrl); # add to navmaps
     if (!$map) {
@@ -4545,6 +4622,10 @@ sub updateGradeByPage {
     $request->print($result);
 
     my $navmap = Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        $request->print(&navmap_errormsg());
+        return;
+    }
     my ($mapUrl, $id, $resUrl) = &Apache::lonnet::decode_symb( $env{'form.page'});
     my $map = $navmap->getResourceByUrl($resUrl); # add to navmaps
     if (!$map) {
@@ -4689,7 +4770,7 @@ sub updateGradeByPage {
 #
 #-------------------------------------------------------------------
 
-#--------------------Scantron Grading-----------------------------------
+#--------------------Bubblesheet (Scantron) Grading-----------------------------------
 #
 #------ start of section for handling grading by page/sequence ---------
 
@@ -4748,7 +4829,9 @@ the homework problem.
   Returns html hidden inputs used to hold context/default values.
 
  Arguments:
-  $symb - $symb of the current resource 
+   $symb - $symb of the current resource
+   $map_error - ref to scalar which will container error if
+                $navmap object is unavailable in &getSymbMap().
 
 =cut
 
@@ -4772,9 +4855,12 @@ sub defaultFormData {
 =cut
 
 sub getSequenceDropDown {
-    my ($symb)=@_;
+    my ($symb,$map_error)=@_;
     my $result='<select name="selectpage">'."\n";
-    my ($titles,$symbx) = &getSymbMap();
+    my ($titles,$symbx) = &getSymbMap($map_error);
+    if (ref($map_error)) {
+        return if ($$map_error);
+    }
     my ($curpage)=&Apache::lonnet::decode_symb($symb); 
     my $ctr=0;
     foreach (@$titles) {
@@ -5040,7 +5126,12 @@ sub scantron_selectphase {
     my ($r,$file2grade) = @_;
     my ($symb)=&get_symb($r);
     if (!$symb) {return '';}
-    my $sequence_selector=&getSequenceDropDown($symb);
+    my $map_error;
+    my $sequence_selector=&getSequenceDropDown($symb,\$map_error);
+    if ($map_error) {
+        $r->print('<br />'.&navmap_errormsg().'<br />');
+        return;
+    }
     my $default_form_data=&defaultFormData($symb);
     my $grading_menu_button=&show_grading_menu_form($symb);
     my $file_selector=&scantron_uploads($file2grade);
@@ -5199,7 +5290,7 @@ sub scantron_selectphase {
               &Apache::loncommon::start_data_table_row()."\n".
               '<td colspan="2">'."\n".
               '<input type="hidden" name="command" value="checksubmissions" />'."\n".
-              '<input type="submit" value="'.&mt('Review Scantron Data and Submission Records').'" />'."\n".
+              '<input type="submit" value="'.&mt('Review Bubblesheet Data and Submission Records').'" />'."\n".
               '</td>'."\n".
               &Apache::loncommon::end_data_table_row()."\n".
               &Apache::loncommon::end_data_table()."\n".
@@ -6214,7 +6305,12 @@ sub scantron_validate_file {
     $r->print('<p>'.&mt('Gathering necessary information.').'</p>');$r->rflush();
     #get the student pick code ready
     $r->print(&Apache::loncommon::studentbrowser_javascript());
-    my $max_bubble=&scantron_get_maxbubble();
+    my $nav_error;
+    my $max_bubble=&scantron_get_maxbubble(\$nav_error);
+    if ($nav_error) {
+        $r->print(&navmap_errormsg());
+        return '';
+    }
     my $result=&scantron_form_start($max_bubble).$default_form_data;
     $r->print($result);
     
@@ -6626,6 +6722,10 @@ sub scantron_validate_sequence {
     my ($r,$currentphase) = @_;
 
     my $navmap=Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        $r->print(&navmap_errormsg());
+        return (1,$currentphase);
+    }
     my (undef,undef,$sequence)=
 	&Apache::lonnet::decode_symb($env{'form.selectpage'});
 
@@ -6658,7 +6758,12 @@ sub scantron_validate_ID {
     my %scantron_config=&get_scantron_config($env{'form.scantron_format'});
     my ($scanlines,$scan_data)=&scantron_getfile();
     
-    &scantron_get_maxbubble();	# parse needs the bubble_lines.. array.
+    my $nav_error;
+    &scantron_get_maxbubble(\$nav_error); # parse needs the bubble_lines.. array.
+    if ($nav_error) {
+        $r->print(&navmap_errormsg());
+        return(1,$currentphase);
+    }
 
     my %found=('ids'=>{},'usernames'=>{});
     for (my $i=0;$i<=$scanlines->{'count'};$i++) {
@@ -7211,7 +7316,12 @@ sub scantron_validate_CODE {
 
     my %allcodes=&get_codes();
 
-    &scantron_get_maxbubble();	# parse needs the lines per response array.
+    my $nav_error;
+    &scantron_get_maxbubble(\$nav_error); # parse needs the lines per response array.
+    if ($nav_error) {
+        $r->print(&navmap_errormsg());
+        return(1,$currentphase);
+    }
 
     my ($scanlines,$scan_data)=&scantron_getfile();
     for (my $i=0;$i<=$scanlines->{'count'};$i++) {
@@ -7265,7 +7375,12 @@ sub scantron_validate_doublebubble {
     #get scantron line setup
     my %scantron_config=&get_scantron_config($env{'form.scantron_format'});
     my ($scanlines,$scan_data)=&scantron_getfile();
-    &scantron_get_maxbubble();	# parse needs the bubble line array.
+    my $nav_error;
+    &scantron_get_maxbubble(\$nav_error); # parse needs the bubble line array.
+    if ($nav_error) {
+        $r->print(&navmap_errormsg());
+        return(1,$currentphase);
+    }
 
     for (my $i=0;$i<=$scanlines->{'count'};$i++) {
 	my $line=&scantron_get_line($scanlines,$scan_data,$i);
@@ -7283,6 +7398,8 @@ sub scantron_validate_doublebubble {
 
 
 sub scantron_get_maxbubble {
+    my ($nav_error) = @_;
+
     if (defined($env{'form.scantron_maxbubble'}) &&
 	$env{'form.scantron_maxbubble'}) {
 	&restore_bubble_lines();
@@ -7293,6 +7410,12 @@ sub scantron_get_maxbubble {
 	&Apache::lonnet::decode_symb($env{'form.selectpage'});
 
     my $navmap=Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        if (ref($nav_error)) {
+            $$nav_error = 1;
+        }
+        return;
+    }
     my $map=$navmap->getResourceByUrl($sequence);
     my @resources=$navmap->retrieveResources($map,\&scantron_filter,1,0);
 
@@ -7382,7 +7505,11 @@ sub scantron_validate_missingbubbles {
     #get scantron line setup
     my %scantron_config=&get_scantron_config($env{'form.scantron_format'});
     my ($scanlines,$scan_data)=&scantron_getfile();
-    my $max_bubble=&scantron_get_maxbubble();
+    my $nav_error;
+    my $max_bubble=&scantron_get_maxbubble(\$nav_error);
+    if ($nav_error) {
+        return(1,$currentphase);
+    }
     if (!$max_bubble) { $max_bubble=2**31; }
     for (my $i=0;$i<=$scanlines->{'count'};$i++) {
 	my $line=&scantron_get_line($scanlines,$scan_data,$i);
@@ -7442,13 +7569,24 @@ sub scantron_process_students {
     my $classlist=&Apache::loncoursedata::get_classlist();
     my %idmap=&username_to_idmap($classlist);
     my $navmap=Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        $r->print(&navmap_errormsg());
+        return '';
+    }  
     my $map=$navmap->getResourceByUrl($sequence);
     my @resources=$navmap->retrieveResources($map,\&scantron_filter,1,0);
     my (%grader_partids_by_symb,%grader_randomlists_by_symb);
     &graders_resources_pass(\@resources,\%grader_partids_by_symb,
                             \%grader_randomlists_by_symb);
+    my $resource_error;
     foreach my $resource (@resources) {
-        my $ressymb = $resource->symb();
+        my $ressymb;
+        if (ref($resource)) {
+            $ressymb = $resource->symb();
+        } else {
+            $resource_error = 1;
+            last;
+        }
         my ($analysis,$parts) =
             &scantron_partids_tograde($resource,$env{'request.course.id'},
                                       $env{'user.name'},$env{'user.domain'},1);
@@ -7460,6 +7598,10 @@ sub scantron_process_students {
             }
         }
     }
+    if ($resource_error) {
+        $r->print(&navmap_errormsg());
+        return '';
+    }
 
     my ($uname,$udom);
     my $result= <<SCANTRONFORM;
@@ -7474,8 +7616,8 @@ SCANTRONFORM
     
     my $lock=&Apache::lonnet::set_lock(&mt('Grading bubblesheet exam'));
     my $count=&get_todo_count($scanlines,$scan_data);
-    my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin($r,'Scantron Status',
- 				    'Scantron Progress',$count,
+    my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin($r,'Bubblesheet Status',
+ 				    'Bubblesheet Progress',$count,
 				    'inline',undef,'scantronupload');
     &Apache::lonhtmlcommon::Update_PrgWin($r,\%prog_state,
 					  'Processing first student');
@@ -7484,7 +7626,12 @@ SCANTRONFORM
     my $i=-1;
     my $started;
 
-    &scantron_get_maxbubble();	# Need the bubble lines array to parse.
+    my $nav_error;
+    &scantron_get_maxbubble(\$nav_error); # Need the bubble lines array to parse.
+    if ($nav_error) {
+        $r->print(&navmap_errormsg());
+        return '';
+    }
 
     # If an ssi failed in scantron_get_maxbubble, put an error message out to
     # the user and return.
@@ -7525,9 +7672,15 @@ SCANTRONFORM
  	}
   	($uname,$udom)=split(/:/,$uname);
 
-        my %partids_by_symb;
+        my (%partids_by_symb,$res_error);
         foreach my $resource (@resources) {
-            my $ressymb = $resource->symb();
+            my $ressymb;
+            if (ref($resource)) {
+                $ressymb = $resource->symb();
+            } else {
+                $res_error = 1;
+                last;
+            }
             if ((exists($grader_randomlists_by_symb{$ressymb})) ||
                 (ref($grader_partids_by_symb{$ressymb}) ne 'ARRAY')) {
                 my ($analysis,$parts) =
@@ -7538,6 +7691,12 @@ SCANTRONFORM
             }
         }
 
+        if ($res_error) {
+            &scantron_add_delay(\@delayqueue,$line,
+                                'An error occurred while grading student '.$uname,2);
+            next;
+        }
+
 	&Apache::lonxml::clear_problem_counter();
   	&Apache::lonnet::appenv($scan_record);
 
@@ -7709,15 +7868,17 @@ sub scantron_upload_scantron_data {
     my $syllabuslink = '<a href="javascript:ToSyllabus();">'.&mt('Syllabus').'</a>'.
                        ('&nbsp'x2).&mt('(shows course personnel)'); 
     my $default_form_data=&defaultFormData(&get_symb($r,1));
+    my $nofile_alert = &mt('Please use the browse button to select a file from your local directory.');
+    my $nocourseid_alert = &mt("Please use the 'Select Course' link to open a separate window where you can search for a course to which a file can be uploaded.");
     $r->print('
 <script type="text/javascript" language="javascript">
     function checkUpload(formname) {
 	if (formname.upfile.value == "") {
-	    alert("'.&mt('Please use the browse button to select a file from your local directory.').'");
+	    alert("'.$nofile_alert.'");
 	    return false;
 	}
         if (formname.courseid.value == "") {
-            alert("'.&mt('Please use the \"Select Course\" link to open a separate window where you can search for a course to which a file can be uploaded.').'");
+            alert("'.$nocourseid_alert.'");
             return false;
         }
 	formname.submit();
@@ -7759,7 +7920,7 @@ sub scantron_upload_scantron_data {
   &Apache::lonhtmlcommon::end_pick_box().'<br />
 
 <input name="command" value="scantronupload_save" type="hidden" />
-<input type="button" onClick="javascript:checkUpload(this.form);" value="'.&mt('Upload Scantron Data').'" />
+<input type="button" onClick="javascript:checkUpload(this.form);" value="'.&mt('Upload Bubblesheet Data').'" />
 </form>
 ');
     return '';
@@ -7777,7 +7938,7 @@ sub scantron_upload_scantron_data_save {
     if (!&Apache::lonnet::allowed('usc',$env{'form.domainid'}) &&
 	!&Apache::lonnet::allowed('usc',
 			    $env{'form.domainid'}.'_'.$env{'form.courseid'})) {
-	$r->print(&mt("You are not allowed to upload Scantron data to the requested course.")."<br />");
+	$r->print(&mt("You are not allowed to upload bubblesheet data to the requested course.")."<br />");
 	if ($symb) {
 	    $r->print(&show_grading_menu_form($symb));
 	} else {
@@ -7966,6 +8127,10 @@ sub checkscantron_results {
     my $classlist=&Apache::loncoursedata::get_classlist();
     my %idmap=&Apache::grades::username_to_idmap($classlist);
     my $navmap=Apache::lonnavmaps::navmap->new();
+    unless (ref($navmap)) {
+        $r->print(&navmap_errormsg());
+        return '';
+    }
     my $map=$navmap->getResourceByUrl($sequence);
     my @resources=$navmap->retrieveResources($map,\&scantron_filter,1,0);
     my (%grader_partids_by_symb,%grader_randomlists_by_symb);
@@ -7980,12 +8145,16 @@ sub checkscantron_results {
     my %completedstudents;
 
     my $count=&Apache::grades::get_todo_count($scanlines,$scan_data);
-    my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin($r,'Scantron/Submissions Comparison Status',
-                                    'Progress of Scantron Data/Submission Records Comparison',$count,
+    my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin($r,'Bubblesheet/Submissions Comparison Status',
+                                    'Progress of Bubblesheet Data/Submission Records Comparison',$count,
                                     'inline',undef,'checkscantron');
     my ($username,$domain,$started);
-
-    &scantron_get_maxbubble();  # Need the bubble lines array to parse.
+    my $nav_error;
+    &scantron_get_maxbubble(\$nav_error); # Need the bubble lines array to parse.
+    if ($nav_error) {
+        $r->print(&navmap_errormsg());
+        return '';
+    }
 
     &Apache::lonhtmlcommon::Update_PrgWin($r,\%prog_state,
                                           'Processing first student');
@@ -8058,14 +8227,14 @@ sub checkscantron_results {
                 if ($scandata{$pid} eq $record{$pid}) {
                     my $css_class = ($passed % 2)?'LC_odd_row':'LC_even_row';
                     $okstudents .= '<tr class="'.$css_class.'">'.
-'<td>'.&mt('Scantron').'</td><td>'.$showscandata.'</td><td rowspan="2">'.$last.'</td><td rowspan="2">'.$pid.'</td>'."\n".
+'<td>'.&mt('Bubblesheet').'</td><td>'.$showscandata.'</td><td rowspan="2">'.$last.'</td><td rowspan="2">'.$pid.'</td>'."\n".
 '</tr>'."\n".
 '<tr class="'.$css_class.'">'."\n".
 '<td>Submissions</td><td>'.$showrecord.'</td></tr>'."\n";
                     $passed ++;
                 } else {
                     my $css_class = ($failed % 2)?'LC_odd_row':'LC_even_row';
-                    $badstudents .= '<tr class="'.$css_class.'"><td>'.&mt('Scantron').'</td><td><span class="LC_nobreak">'.$scandata{$pid}.'</span></td><td rowspan="2">'.$last.'</td><td rowspan="2">'.$pid.'</td>'."\n".
+                    $badstudents .= '<tr class="'.$css_class.'"><td>'.&mt('Bubblesheet').'</td><td><span class="LC_nobreak">'.$scandata{$pid}.'</span></td><td rowspan="2">'.$last.'</td><td rowspan="2">'.$pid.'</td>'."\n".
 '</tr>'."\n".
 '<tr class="'.$css_class.'">'."\n".
 '<td>Submissions</td><td><span class="LC_nobreak">'.$record{$pid}.'</span></td>'."\n".
@@ -8299,7 +8468,7 @@ sub grading_menu {
     $fields{'command'} = 'scantron_selectphase';
     $url = &Apache::lonhtmlcommon::build_url('grades/',\%fields);
     push(@menu, { url => $url,
-                   name => &mt('Grade/Manage/Review Scantron Forms'),
+                   name => &mt('Grade/Manage/Review Bubblesheets'),
                    short_description =>
             &mt('Grade scantron exams, upload/download scantron data files, and review previously graded scantron exams.')});
     $fields{'command'} = 'verify';
@@ -8985,7 +9154,11 @@ sub assign_clicker_grades {
     my ($symb)=&get_symb($r);
     if (!$symb) {return '';}
 # See which part we are saving to
-    my ($partlist,$handgrade,$responseType) = &response_type($symb);
+    my $res_error;
+    my ($partlist,$handgrade,$responseType) = &response_type($symb,\$res_error);
+    if ($res_error) {
+        return &navmap_errormsg();
+    }
 # FIXME: This should probably look for the first handgradeable part
     my $part=$$partlist[0];
 # Start screen output
@@ -9049,13 +9222,13 @@ ENDHEADER
           my $sum=0;
           my $realnumber=$number;
           for (my $i=0;$i<$number;$i++) {
-             if ($answer[$i]) {
+             if  ($correct[$i] eq '-') {
+                $realnumber--;
+             } elsif ($answer[$i]) {
                 if ($gradingmechanism eq 'attendance') {
                    $sum+=$pcorrect;
-                } elsif ($answer[$i] eq '*') {
+                } elsif ($correct[$i] eq '*') {
                    $sum+=$pcorrect;
-                } elsif ($answer[$i] eq '-') {
-                   $realnumber--;
                 } else {
                    if ($answer[$i] eq $correct[$i]) {
                       $sum+=$pcorrect;
@@ -9089,6 +9262,13 @@ ENDHEADER
     return $result.&show_grading_menu_form($symb);
 }
 
+sub navmap_errormsg {
+    return '<div class="LC_error">'.
+           &mt('An error occurred retrieving information about resources in the course.').'<br />'.
+           &mt('It is recommended that you [_1]re-initialize the course[_2] and then return to this grading page..','<a href="/adm/roles?selectrole=1&newrole='.$env{'request.role'}.'">','</a>').
+           '</div>';
+}
+
 sub handler {
     my $request=$_[0];
     &reset_caches();
@@ -9314,6 +9494,13 @@ ssi_with_retries()
 
 =item  scantron_get_maxbubble() : 
 
+   Arguments:
+       $nav_error  - Reference to scalar which is a flag to indicate a
+                      failure to retrieve a navmap object.
+       if $nav_error is set to 1 by scantron_get_maxbubble(), the 
+       calling routine should trap the error condition and display the warning
+       found in &navmap_errormsg().
+
    Returns the maximum number of bubble lines that are expected to
    occur. Does this by walking the selected sequence rendering the
    resource and then checking &Apache::lonxml::get_problem_counter()
@@ -9379,6 +9566,11 @@ ssi_with_retries()
    Validates all scanlines in the selected file to not have any
    invalid or underspecified student/employee IDs
 
+=item navmap_errormsg() :
+
+   Returns HTML mark-up inside a <div></div> with a link to re-initialize the course.
+   Should be called whenever the request to instantiate a navmap object fails.  
+
 =back
 
 =cut