Index: openacs-4/packages/acs-subsite/www/register/user-join.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-subsite/www/register/user-join.tcl,v
diff -u -r1.12 -r1.13
--- openacs-4/packages/acs-subsite/www/register/user-join.tcl	10 Jan 2007 21:22:09 -0000	1.12
+++ openacs-4/packages/acs-subsite/www/register/user-join.tcl	27 Oct 2014 16:40:01 -0000	1.13
@@ -9,7 +9,7 @@
     @creation-date 2000-2-28
     @cvs-id $Id$
 } {
-    {group_id:integer {[application_group::group_id_from_package_id]}}
+    {group_id:naturalnum,notnull {[application_group::group_id_from_package_id]}}
     {rel_type:notnull "membership_rel"}
     {return_url {}}
 } -properties {
@@ -34,7 +34,7 @@
 set join_policy $group_info(join_policy)
 
 
-if { [exists_and_not_null return_url] } {
+if { ([info exists return_url] && $return_url ne "") } {
     set ret_link "<a href=\"$return_url\">Return to previous page.</a>"
 } else {
     set ret_link ""