3 to 4 post controller problem

I have a 2002 ezgo txt electric non pds system. The cart will not run. I replaced the solenoid, and the speed controller. The cart still does not run. I was wondering if the problem was the fact that my old controller had B+, B-, M- while my new controller has a B+, B-, M-, and now A2. I left the A2 post on the controller empty. Is that the problem or is there more to it.