yes, this seemed to have been the Problem - fortunately it is solved - original map removed from .sys folder, the other remains on SD Card and it works - you are great experts here in this forum :-))

about my JCV file - as stated by Neil - i assume i will need to remove the built-in files and load the new JCV file into the .sys folder, right ?

anything else which Needs to be loaded into .sys ? just to be sure ...