Schneider Senator 92, backgauge

I need help with a problem with the backgauge.
It stops at 408.48 mm when I use the manual push button "Back".
If I press the push button "Fast" and "Back" it drives fine all the way to the limit switch.
If I use a program it won't try to run if the desired set value is over 408mm.
If I move the rear stop to e.g. 650 mm and start a program where the set value is 300 mm, it moves fine to the target.
Does anyone know what could be causing this?