MM-PUR-REQ : Error after upgrade to 46C

[Hendra Suryakusumah]

Dear Workflow Gurus,
 
We're in Upgrading fr 4.0B to 4.6C and having Workflow for MM-PUR-REQ
(WS20000077) which is running well in 4.0B.
After upgrade there is some error message "Work item ##### : Agents of type
A cannot be defined".I have checked both the Workflow Customizing and event
linkage and there are no errors as well as the IMG of PR.
 
Is there someone can give me some advice?
 
Thanks in advance,
Hendra