Returns

I am trying to return to receiving lines in inventory from an ASN--I have the inventory in our receiving subinventory but when I try going through the form --I get this error: Invalid pack/unpack operation

when I try to do a correction --it fails indicating that the inventory does not exist and when I try going through the rcv_transactions_interface on a 'Return to Receiving' I get basically the same erro-

Can anyone advise me as to what is causing this behavior and how to create--it is critical for our org to return these items