I was reviewing the information regard this case and I found that message is sent because a new constraint was created inside the validation, the new constraint is RD_CO_RO_CUS_EXC_DET and it was created on 07.06.2016 (see attached document).
It looks as combination of customer/article should be in a table for processing.
Please could be possible to review with M.Weyer if necessary some information for a successful validation?
I'll be aware of your comments.