I´ve got an problem. I try to create an tool with two grippers at an crane system. I defined the crane as a robot. The two parts (Ink 7 and Ink 8) shout drive independently (linear kinematics) apart and together (j5 and j6). I tried to connect each gripper with one end of the moving arms, but when I move them, they are both attached at one (picture 2+3).