Partner functionality in release order

Dear Gurus,

I have created a contract with partner functionality.

I created a Purchase Requisition referring contract (Using source of supply). I need to create Po in ME21N by adopting PR. System copies all the other details but not partner details. I need to enter partner details manually in PO.

But When I create a PO in ME21N by adopting the same contract, partner details are automatically copied from contract.

Please suggest me what should I do If my PO should copy partner details of contract (while creating PO adopting PR)

Regards,

Sastry