--- loncom/interface/statistics/lonproblemanalysis.pm	2005/04/19 13:59:34	1.121
+++ loncom/interface/statistics/lonproblemanalysis.pm	2005/11/07 22:09:00	1.122
@@ -1,6 +1,6 @@
 # The LearningOnline Network with CAPA
 #
-# $Id: lonproblemanalysis.pm,v 1.121 2005/04/19 13:59:34 matthew Exp $
+# $Id: lonproblemanalysis.pm,v 1.122 2005/11/07 22:09:00 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -341,7 +341,9 @@ sub numerical_plot_percent {
     while (my ($ans,$submissions) = each(%$responses)) {
         while (my ($submission,$counts) = each(%$submissions)) {
             my ($correct_count,$incorrect_count) = @$counts;
-            my $scaled_value = 100*($submission-$ans)/abs($ans);
+	    my $scaled_value = 
+		($ans) ? 100*($submission-$ans)/abs($ans)
+		       : 0;
             if ($scaled_value < $bins[0]) {
                 $bins[0]=$scaled_value -1;
             }