Diagnosis
This purchase requisition has been created from asales document. It can only becopied into a single purchase order item, that is, it is not possibleto reference the requisition in more than one order item. If you wantto order only part of the total quantity, the remaining quantity ofthis requisition will remain open.
You will then only be able to close this requisition by changing therelevant sales document.
Neither is it possible for the sales document itself to be completelyclosed as a result of a partial order.

Procedure
Since a sales document containing this quantity exists in the systemfor this transaction, you should copy the entire requisition quantityinto the PO item.