Index: trunk/ippScripts/scripts/diff_skycell.pl
===================================================================
--- trunk/ippScripts/scripts/diff_skycell.pl	(revision 16308)
+++ trunk/ippScripts/scripts/diff_skycell.pl	(revision 16563)
@@ -253,5 +253,5 @@
 
     warn($msg);
-    if ($diff_id and not $no_update) {
+    if (defined $diff_id and not $no_update) {
 	my $command = "$difftool -adddiffskyfile -diff_id $diff_id -code $exit_code";
 	$command .= " -dbname $dbname" if defined $dbname;