diff --git a/addons/base_calendar/base_calendar.py b/addons/base_calendar/base_calendar.py
index 29563633896..6720b4d3e4a 100644
--- a/addons/base_calendar/base_calendar.py
+++ b/addons/base_calendar/base_calendar.py
@@ -529,7 +529,8 @@ property or property parameter."),
                 defaults = {'user_id': vals.user_id.id, 'organizer_id': vals.ref.user_id.id,'duration':res[0]['duration'],'class':res[0]['class']}
                 mod_obj.copy(cr, uid, vals.ref.id, default=defaults, context=context)
             meeting_id = meeting_obj.search(cr, uid, [('attendee_ids','=',vals.id)],context = context)
-            meeting_obj.message_post(cr, uid, meeting_id, body=_(("%s has Accept the meeting") % (vals.cn)), context=context)
+            if meeting_id:
+                meeting_obj.message_post(cr, uid, meeting_id, body=_(("%s has Accept the meeting") % (vals.cn)), context=context)
             self.write(cr, uid, vals.id, {'state': 'accepted'}, context)
         return True