Xbox 360 vertical analog axis not working right?

I'm making a game using the 360 controller and everything works up until now. The issue is the vertical axis on both analog sticks aren't working like they should. The sensitivity range isn't registering. It just jumps from 0 to 15 (in this case) with barely any pressure on the analog stick. The horizontal(X and 4th) axis work fine but for some reason the vertical(Y and 5th) axis don't. I've checked to see if the vertical axis are assigned to other buttons but they aren't. Anyone have this issue before? Any help would be appreciated.