Diagnosis
You have attempted to delete or block an item whose GR and POquantities differ.
You can only delete or block items whose processing has been completed.This means that the delivered quantity of the goods must be greaterthan or equal to the quantity ordered (less the underdeliverytolerance).

Procedure
If you nevertheless want to delete or block the item, proceed asfollows:
Press F12=Cancel.
Change the PO quantity of the item, so that
GR quantity >= PO quantity - underdelivery tolerance.
Select the item and choose the option "Delete" or "Block" again.