Axiom 49 - never been able to get drum pads to work

I'm using an Axiom 49 M-Audio keyboard. I seem to be able to assign controls with the sliders and knobs, but when I try to assign any of the 8 drum pads on the right of the keyboard they don't do anything. It seems to "See" the pads, they do respond in the transport window as (from TtoB, LtoR) 71, 105, 106, 107, 74, 102, 103 and 104. However then they don't make any sound ever.

I recently tried "Learn"ing them in MainStage for the first time. Still Nothing.

Please help. I would really appreciate it. Sorry if this is completely rudimentary, but any direction would help.

Thank you!