PO qty Incorrect in MRP

hi Gurus,

i have facinga problem in MD04 screen in which against a Shipping Notification iam receving the same qty for recipt and available qty,where its subcontracting PO with mvt TYPE 543 in which

these steps are taking

PO

Inbound delivery

GR

are taking place

were if a qty is 500 in which 168 consu,med it should show the remaing 332 qty in PO.

but it is showing 500 qty ...plz guide me with ur valuable advice

Regards

NNeeti