Please do not add questions to the very old posts but create a new post instead.
We ran into this message just a few days ago. I googled it but couldn't find a solution (although I do remember an existing post regarding MIRO, also search for OSS notes).
In our case (customer invoice, not MIRO) it turned out that there were taxable and non-taxable materials on the same invoice. For some reason this is not allowed. Fortunately, this message occurs in only one FM, so if you do a 'where-used' in SE91, you'll see what's happening. It's not that difficult to debug, took me about an hour to figure it out beginning through end.