problem with BAPI_PO_RELEASE in workflow

Hi Experts,

I have a backgrouond task for PO releases. in the method of the task , iam calling a BAPI, 'BAPI_PO_RELEASE' .when iam executing the workflow through SWUS the BAPI returnig parameters like new release code etc successfully but release strategy is not getting updated in the PO.please let me know what can be the problem?

Thanks & Regards,

Sarath