Purchase Order blocked during approval of final release code

Hi All,

  I have a custom workflow for Purchase Order approval process.

The issue is sometimes , while approving PO through work item - > user clicks on APPROVE button from business workplace ,

Workflow gets completed but PO is in blocked status.

The reason behind this , sometimes the PO# will be blocked by some other user OR by some background job,

We are calling BAPI to release the PO in custom method.

Is there any way to control this in workflow?

Please help.

Thanks,

Arpita