Stepmania 5 2a beta not accepting arrow input in songs

- I just installed the most recent version of Stepmania for Mac
- When I plug in my pad and go to the Test Input screen. Stepmania sees my gamepad. However, if I press any buttons on the gamepad, Stepmania does not see those button presses. If I unplug/plug it in, it doesn't change. Stepmania sees that my pad exists but it can't see the button presses.
- My pad works fine on my PS2 (it has multiple outputs)

Have you mapped your pad's buttons to game buttons? In the default theme, this can be done under Config Key/Joy Mappings.

I have tried mapping the pad's buttons to game buttons in Config Key/Joy Mappings. But whenever I tried to register buttons on my pad, the game wouldn't respond. So I was thinking that I could manually map the buttons by going to Test Input and finding out the names of each button. But they won't even show up when I press them on Test Input.

This could be a problem with my pad itself, but it seems weird that it works on other systems. Do you know how I could troubleshoot this further?

I did a little investigation this week and this is what I found:

My DDR pad has four outputs: Gamecube, PS2, Xbox (original), and USB...or so I assumed. I think the USB might actually be intended for Xbox 360. The reason I say this is because I have a Mac, and when I tried hooking my pad up to my friend's laptop, which is a PC, it worked fine. So...I think I'm going to try to get a PS2-to-USB adapter and see if I could work around it that way.