Error in notification mail in po release
i encounter a problem in notification mail activity. actually my wflow gets trigerred wen a po is created. It has four levels of approval, in the activity i have given the notification agent as the po creator the wen the first approver releases the po and saves the workitem status is set to be inprocess itself it doesnt get the status as completed.but the po reaches the second approvers inbox and he also effects the release but there also the workitem status is set to inprocess .
like wise it happens with the remaining users but the document is released but the notification is not sent to the po creator.
When i view the technical details of that workitem there is an error stating
Terminating event recieved : notification of completion cannot be generated
problems occures during generation of mail
if_swf_utl_mail~send error 9 when calling service so_object_send
please do help me with this error.