Workflow Error : method RELEASE_PURCH_DOC cannot be executed
I am getting following errors in single Workflow for PURCHASE ORDER RELEASE
1. User 01101685 already processing Purchase order 30 00938139
2. Work item 000017292981: Object PO#/User method RELEASE_PURCH_DOC cannot be executed
Inside the Method RELEASE_PURCH_DOC function module
'BAPI_PO_RELEASE' is called.
and I have checked in container values , I have found that PO Release code is not updated from BAPI_PO_RELEASE.
Please help on this.