The Purchase Order is keyed in by the buying manager. The bill is keyed by AP. Nothing is uploaded. 

The purchase order and bill are from the same vendor. Simply put the Purchase Order is NOT on the list of Select Related Transactions for that vendor. 

We ended up deleting the Item Receipt and then the Purchase Order appeared on the list of Select Related Transactions. We hope this is an isolated incident because we have plenty of purchase orders that need to be matched to bills. 

There's definitely something amiss in the dbase/program matching process.