Source Details mot populated in requisition form

Dear all,

I had created an ASL and attached an contract PA , my problem I can see the supplier being populated but when I click on source details I an unable to see the Contract PO that I had referenced. any ideas why supplier is being populated but not PO number in source details. I am testing Pricing for Purchasing

In the screen shot we can see supplier being populated but not the Contract PO defined in ASL

Regards