Thanks for your two advices.
I made both, and now, it works !

Thanks a lot.

Installation of my NL2000 sceneries in the default directory (C:/NL2000). The problem appairs at the end of the scenery install process. A message box informs that the access to C:\ProgramData\Microsoft\FSX\scenery.cfg.nl2 is refused. The new scenery is normally installed but the Installer can't giv...