Decrease Quantity converts Scrap material to Good Parts. It is used to recover/convert scrap parts or material into good parts. It makes no sense to do this on a Scrap Item that will always be reported as scrap if it gets run. In fact, the Decrement Qty will do exactly the opposite of what the user is trying to do. It will take a scrap part, intended to be scrap and be reported as scrap and report it as good material.

A Decrement Quantity on a Scrap item is no longer allowed.