Diagnosis
By changing the item, the +/- sign of payment would change. The paymentmethod provided could thus no longer be used. The payment affected isnot the one being edited, but a different one which contains an item ofthe central invoice to be blocked.

System Response
The change is rejected.

Procedure
If you want to change several items in payment, check whether thechanges can be made in another sequence.
For example, if an invoice of 1000 and a credit memo of 100 arecontained in a payment of 950, you can block the credit memo first andfinally to 50. The reverse sequence is not possible because a paymentamount of 50- would result as an intermediate value.