Logged voucher match to PO giving Asynchronous error

While redistributing a logged voucher to PO receipt I received an Asynchronous error. This occurs when an invoice line is matched to a receipt that has been partially received. Example. PO was received for a Qty of 2 on an order oie with a QTY of 6. The same line was received later for the remaining 4 lines. This gives two PO receipt lines I match the logged voucher against the receipt for oth lines and get the Asynchronous error. I cleared CACHE but that did not resolve the issue.