Index: openacs-4/packages/acs-templating/tcl/list-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-templating/tcl/list-procs.tcl,v
diff -u -r1.39.2.1 -r1.39.2.2
--- openacs-4/packages/acs-templating/tcl/list-procs.tcl	14 Dec 2006 13:55:10 -0000	1.39.2.1
+++ openacs-4/packages/acs-templating/tcl/list-procs.tcl	24 Jan 2007 18:30:08 -0000	1.39.2.2
@@ -1071,7 +1071,7 @@
                         # Update subtotals
                         incr __agg_group_counter($__element_properties(name))
                         set __agg_group_sum($__element_properties(name)) \
-                            [expr $__agg_group_sum($__element_properties(name)) + [set $__element_properties(name)]]
+                            [expr $__agg_group_sum($__element_properties(name)) + [expr {[string is double [set $__element_properties(name)]] ? [set $__element_properties(name)] : 0}]]
                     }
 
                     switch $__element_properties(aggregate) {