How do I 360 A button working

I have followed a couple of tutorials and I can't seem to get the A button for the 360 controller working on my Mac with Unity my unity game.

Here is a screen shot of my settings.

The button will be used to fire a shot in my game. Here is the code that I have for Firing.

 if(Input.GetKeyDown(KeyCode.Space) || Input.GetButtonDown("360_AButton"))
 {
     Instantiate(shot, shotSpawn.position, shotSpawn.rotation);
 }

The actual joystick on the controller seems to work for controlling my ship just fine without having to do anything. I just can't seem to get it to work with the buttons on the controller.