--- loncom/interface/spreadsheet/Spreadsheet.pm	2005/04/07 06:56:23	1.41
+++ loncom/interface/spreadsheet/Spreadsheet.pm	2005/04/21 17:29:16	1.42
@@ -1,5 +1,5 @@
 #
-# $Id: Spreadsheet.pm,v 1.41 2005/04/07 06:56:23 albertel Exp $
+# $Id: Spreadsheet.pm,v 1.42 2005/04/21 17:29:16 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -937,7 +937,8 @@ sub sett {
             $t{$cell}=~s/(^|[^\"\'])([A-Za-z]\d+)/$1\$sheet_values\{\'$2\'\}/g;
             $t{$cell}=~s/(^|[^\"\'])\[([^\]]+)\]/$1.$self->expandnamed($2)/ge;
         } elsif  ( $col  =~ /^[A-Z]$/  ) {
-            if ($formula !~ /^\!/ && exists($self->{'constants'}->{$cell})) {
+            if ($formula !~ /^\!/ && exists($self->{'constants'}->{$cell})
+		&& $self->{'constants'}->{$cell} ne '') {
                 my $data = $self->{'constants'}->{$cell};
                 $t{$cell} = $data;
             }