Unexpected behavior during calibration of x-axis

Hello,
during the calibration of the x-axis, the farmbot moves to the home point instead of the other end of the axis. The y and z-axis moves from the homing point to the other end of the axis. This results in a correct calibration of the y and z-axis, but not the x-axis. It displayed that the x -axis is only a few centimeters long (cause the farmbot moves only a few millimeters along the x-axis to the homing point). I can't get the calibration of the x-axis working with the Python-API, neither the web App.