Doublechecked firmware, everything is correct.
I swaped the drivers, but, as the swaped axis have wrong height-informations now, I can't print like that, can I?
What I noticed after swaping the drivers is, that, when I move the axis 1mm, the swaped axis do not both move 1mm as they should, the y-axis with the z-stepperdriver is definitely moving more. Is that normal, when there is the wrong driver connected..? If a video or something would help I can send you one.