[MrB]

I've been working to help trevor solve that problem. The parts can slide freely if dragged with the mouse, and if you manually set an offset at 1 inch increments it works without any errors. BUT , as soon as he tries to drive the constraint it moves about 1-2 inchs, stops, and then pops up the erros that he posted above.

He's been working on this for 2 days and we're starting to run out of excuses as to why it won't work.