[fargus111111111]

I have built a "tank drive" control similar to what I think you are looking for for one of our demo robots. Just to clarify, you are trying to use the two Y-values from the sticks on the controller to control your right and left side independent of each other. The two numeric inputs on the "Tank Drive" VI are the two joystick input values. A single instance of the "Tank Drive" VI will control both the right and left sides. Having multiple drive VIs running at the same time will cause problems.

As a side note, this is a hard drive style to get used to if you have done a lot of driving with single stick controls.