--- loncom/homework/imageresponse.pm	2010/12/19 01:08:11	1.100
+++ loncom/homework/imageresponse.pm	2011/06/07 17:27:37	1.101
@@ -2,7 +2,7 @@
 # The LearningOnline Network with CAPA
 # image click response style
 #
-# $Id: imageresponse.pm,v 1.100 2010/12/19 01:08:11 raeburn Exp $
+# $Id: imageresponse.pm,v 1.101 2011/06/07 17:27:37 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -631,6 +631,9 @@ sub start_foil {
 	    &Apache::lonxml::warning(&mt('Foils without names exist. This can cause problems to malfunction.'));
 	    $name=$Apache::lonxml::curdepth;
 	}
+        if ($name eq "0") {
+            &Apache::lonxml::error(&mt('Foil name [_1] is not supported. Please choose another name.','<b><tt>'.$name.'</tt></b>'));
+        }
 	if (defined($Apache::response::foilnames{$name})) {
 	    &Apache::lonxml::error(&mt("Foil name [_1] appears more than once. Foil names need to be unique."
                                       ,'<b><tt>'.$name.'</tt></b>'));