add the error message in the example

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@24668 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Constraint/CategoryMembershipState.py

@@ -42,6 +42,7 @@ class CategoryMembershipState(Constraint):
       'portal_type'   : ('Organisation', ),
       'base_category' : ('source',),
       'validation_state': ('validated', ),
+      'message_different_state': 'Organisation must be validated',
     },
   """
   _message_id_list = ['message_different_state']