ja I have physical dynamics on, and when i rotate either the gear or pinion, the other does not move and becomes stuck itself.(Basically one cannot move the other and they and cannot get passed the other) Physically there's nothing wrong with the setup. Gear and pinion in the correct positions and moving in the correct directions. Made the rods that they are on, parallel and so forth. Using the correct distance from the axis of gear and axis of pinion, from their pitch diameters.
Is their some other mate or relationship i need to include to make assembly work?