Just to add, having read through the manual again and looked at the screen shots to see if I remembered what the issue was for me - make sure the enabled box is checked and then hit set which brings up the second smaller window where you select the controller from the drop down and push a button to confirm the assignment (may have to click in the button window, honestly I can't remember) but for a long time I thought there was an issue with the hardware because I only got button 0 which did not work but it was me.