Not blank. But to the old functional area which I have captured in a Z table during the reassigment process. The original reassigment is made through the FMDERIVE table, migrating all MM, FI and FM document from the actual functional area to a new one. The client wants to have a procedure to put the old functional area back as it was in each document. Since using FMDERIVE for both directions is too complicated, I have been trying to overide the new functional area by placing the old one in the field "Functional Area by Default" in the FMCN transaction. I does work for some FI documents but for most of them I keep getting the above mentioned error message.
PS: Ironically, when I turn the rules for the new functional area off, the document comes out with a blank functional area despite there's a value in the default. If only that would be what I needed, but is not.