Multiple Xbox360 Wired Controllers

I'm having trouble getting Unity to take input from multiple Xbox360 Wired controllers at the same time. One controller works fine with all buttons described as 'joystick 1 button #', but 'joystick 2 button #' doesn't work for the second controller. I've just got the controller in the next USB slot over on the computer, and it is being recognized by other programs, so I'm pretty sure it's a problem with my Unity setup. What am i doing wrong? Is there a way to have Unity tell you what input devices it currently recognizes?

OK, well now I feel like a n00b. It doesn't work if I plug a controller in after Unity is already started. However, plugging both controllers in and then starting Unity seemed to do the trick.