--- loncom/interface/loncoursedata.pm	2006/05/18 01:08:51	1.171
+++ loncom/interface/loncoursedata.pm	2006/05/18 18:37:23	1.172
@@ -1,6 +1,6 @@
 # The LearningOnline Network with CAPA
 #
-# $Id: loncoursedata.pm,v 1.171 2006/05/18 01:08:51 raeburn Exp $
+# $Id: loncoursedata.pm,v 1.172 2006/05/18 18:37:23 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -3144,6 +3144,9 @@ sub get_classlist {
 
 sub get_group_memberships {
     my ($classlist,$keylist,$cdom,$cnum) = @_;
+
+    return ({},{}) if (!ref($classlist) || !ref($keylist));
+
     my $cid = $cdom.'_'.$cnum;
     if (!defined($cdom) || !defined($cnum)) {
         $cid =  $env{'request.course.id'};