X and Y axis calibration

Vertex 3D Printer Vertex - Issues while printing
1

Hi,

I’ve a problem with X and Y axis calibration: using auto-home moves the printhead to the right back corner, as it should, and sets X and Y position to (200,200). But when I move the printhead to the left front corner, the position shown is (91,91), not (0,20) (as shown by example in the “calibrating Z axis” manual). So it tries to print an object much bigger than the build plateform.
The Z axis hasn’t this strange behavior, it moves from 100 to 2 without problem.

Any idea on why?

Thanks,
Quentin