getThrottle() returning 0 actually is normal in my experience. Try using getY() instead. (Or go into your controller's settings on your computer and investigate which axes are what)
And, I think you're inputting values out of range. tankDrive should take numbers -1 to 1. (2 is out of range)
And if your robot is normal, a value of -1 or 1 will send your robot speeding towards you before you can disable it.
