[Alan Anderson]

If I'm reading your code correctly, the chassis.arcadeDrive (speed, rot); line will have no effect. Unless button 3 or 4 is pressed, the if statement immediately after it will turn off both speed controllers. Pressing one of those buttons will cause your robot to drive full speed forward or full speed reverse (or perhaps spin in place, depending on your wiring).

If you do want the "full speed" button functionality to remain, I think you should move the arcadeDrive function call into the final else case, replacing the jag.set(0); and jaguar.set(0); lines.