ME59N - Service Purchase Requisition..is it possible ?

Dear friends,

I'd like to know if is possible to create PO automatically via ME59N (job scheduled) from a purchase requisition with item category D-services.

After to enter a sorce in the Purch.Requisition we are trying to create POs automatically to this service PR, same way we do this for materials.

We got the error message saying that PR doesn't exist ...when we try that via ME59N , we only is allowed to create it via ME21N.

best regards,

Alessandro