Hey Tompo thanks for your fast reply. The bones are all merged and the option is also checked. The different distance from one hinge to the second one, is the problem. But this problem doesn't appear when I remove the trace part and change the ent_bonerotate code so that it only makes the bone rotate when I press the key_h.

BTW, thanks for the compliment, I'm still working on the model his skin, but the actual design of the crawler model is finished.