--- loncom/interface/spreadsheet/assesscalc.pm	2005/05/15 02:40:26	1.44
+++ loncom/interface/spreadsheet/assesscalc.pm	2005/05/15 02:49:07	1.45
@@ -1,5 +1,5 @@
 #
-# $Id: assesscalc.pm,v 1.44 2005/05/15 02:40:26 albertel Exp $
+# $Id: assesscalc.pm,v 1.45 2005/05/15 02:49:07 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -833,7 +833,10 @@ sub sett {
     while (my ($cell,$formula) = each(%{$self->{'formulas'}})) {
 	next if ($cell =~ /template_/);
         if ($cell =~ /^A/ && $cell ne 'A0') {
-            if ($formula !~ /^\!/) {
+	    if ($formula !~ /^\!/ 
+		&& exists($self->{'constants'}->{$formula}) 
+		&& $self->{'constants'}->{$formula} ne ''
+		) {
 		$Apache::Spreadsheet::sheet_values{$cell}=
 		    eval($self->{'constants'}->{$formula});
             }