Index: openacs-4/packages/acs-templating/tcl/date-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-templating/tcl/date-procs.tcl,v
diff -u -r1.20 -r1.21
--- openacs-4/packages/acs-templating/tcl/date-procs.tcl	22 Sep 2003 19:59:57 -0000	1.20
+++ openacs-4/packages/acs-templating/tcl/date-procs.tcl	30 Sep 2003 19:24:09 -0000	1.21
@@ -733,7 +733,9 @@
 
   if {$interval_size > 1} {
     # round minutes or seconds to nearest interval
-    set value [expr $value-$value%$interval_size]
+    if { ![empty_string_p $value] } {
+      set value [expr $value-$value%$interval_size]
+    }
   }
 
   return [template::widget::menu $name $options [list $value] attributes]