Xbox one controller

I'm trying to play borderlands 2 on pc with an xbox ONE controller through steam. It lets me select the game and start it up and play with the settings on the start up menu with the controller, but once the game starts up it doesnt let me use the contoller at all. I have to use the mouse... I even tried to mess with the settings in game. I've googled everything I can think of. What can I do?