In sample data, check the Entered document filter, and delete all PO's except for PO#-0000008,7,5, and 4 They should be in descending order (8,7,5,4). Highlight PO# 8, receive it,post, yes to completed, OK to save document, and No to print receipt now (I always print receipts after I've received everything). The next PO is highlighted (#7), and the receipt and complete buttons are greyed out.

Hope this helps.