Diagnosis
You have changed the confirmation control key in a schedulingagreement.
Either this is not possible, or the confirmation control key entered, (
V1) cannot be used.

System Response
You can only replace an existing confirmation control key by anotherone if no confirmations or goods receipts have yet been entered for anitem.
Acknowledgments of receipt (proof of delivery)
If confirmations and goods receipts have already been entered for anitem, you must use a new confirmation control key when implementingacknowledgments of receipt (LE "proof of delivery" (POD)functionality). This confirmation control key must be a) identical tothe previous one and b) POD-relevant.
That means that the new confirmation control key must define the sameconfirmation categories and these confirmation categories must have thesame indicators for MRP-relevant, GR-relevant and GRassignment.
Hidden text in German does NOT need to be translated. (Writer's notes)

Procedure
Check and change your entries if necessary.
Note
You maintain the confirmation control key in Customizing forPurchasing under Confirmations -> Set Up ConfirmationControl.