--- loncom/homework/inputtags.pm	2004/10/21 02:43:34	1.153
+++ loncom/homework/inputtags.pm	2004/11/06 01:11:38	1.154
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # input  definitons
 #
-# $Id: inputtags.pm,v 1.153 2004/10/21 02:43:34 albertel Exp $
+# $Id: inputtags.pm,v 1.154 2004/11/06 01:11:38 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -528,10 +528,15 @@ sub hidealldata {
 
 sub setgradedata {
     my ($award,$msg,$id,$previously_used) = @_;
-    # if the student already has it correct, don't modify the status
-    if ($Apache::lonhomework::scantronmode && defined($ENV{'form.CODE'})) {
+    if ($Apache::lonhomework::scantronmode && 
+	&Apache::lonnet::validCODE($ENV{'form.CODE'})) {
 	$Apache::lonhomework::results{"resource.CODE"}=$ENV{'form.CODE'};
+    } elsif ($Apache::lonhomework::scantronmode && 
+	     $ENV{'form.CODE'} eq '' &&
+	     $Apache::lonhomework::history{"resource.CODE"} ne '') {
+	$Apache::lonhomework::results{"resource.CODE"}='';
     }
+
     if (!$Apache::lonhomework::scantronmode &&
 	$Apache::inputtags::status['-1'] ne 'CAN_ANSWER' &&
 	$Apache::inputtags::status['-1'] ne 'CANNOT_ANSWER') {
@@ -540,7 +545,10 @@ sub setgradedata {
     } elsif ( $Apache::lonhomework::history{"resource.$id.solved"} !~
 	      /^correct/ || $Apache::lonhomework::scantronmode ||
 	      lc($Apache::lonhomework::problemstatus) eq 'no') {
-	#handle assignment of tries and solved status
+        # the student doesn't already have it correct,
+	# or we are in a mode (scantron orno problem status) where a correct 
+        # can become incorrect
+	# handle assignment of tries and solved status
 	my $solvemsg;
 	if ($Apache::lonhomework::scantronmode) {
 	    $solvemsg='correct_by_scantron';