Hi, I have a problem with my Chevy Aveo 2010 Automatic gearbox. The gearbox doesn't change gears. When I start it and put in on Drive then it goes normal but when it's supposed to change to a higher gear then it starts over raving as if it is in Neutral (I think it goes into neutral). Could this be mechanical or an electrical fault? How do I go about diagnosing the problem?