How to trigger Matrix cell via MIDI Controller?

I have never used the Matrix View up until tonight.  Curiosity got the best of me so I began to experiment.  I dragged a few audio clips from one of my songs into a folder and imported a clip from the folder to a cell in the MV.

I can click on the cell or column and it plays fine.  When I try to assign the cell (or even the column) via MIDI Learn, the clip does not trigger.  I know the nanoPAD is sending a MIDI message into Sonar as I set up a MIDI track just to see the signal show up.  I also tried it with my M-Audio Keystation but no joy even though Sonar is receiving a signal from the unit too.

Any suggestions?

This is not critical but I thought it might be fun to set it up for a non-musician friend of mine to help "play" some of the parts whilst I strum a six string.

Thanks.

X1's reference manual suggests the following in which I have followed several times but to no avail:

To trigger a cell or column via MIDI remote control

You can trigger a cell or column via MIDI remote control, but you must first specify the MIDI message that should trigger the cell or column.

    1. Right-click the cell or Column Trigger that you would like to trigger via MIDI remote     control, and select MIDI Learn from the pop-up menu.  The cell has a yellow outline. The     next MIDI event the Matrix receives will be assigned to all cells that are in MIDI Learn     mode.

         Note: If the Cell MIDI Trigger button in the Matrix view toolbar is disabled, it will               automatically be enabled when a cell is in MIDI Learn mode.

    2. Press the desired key, pad or button on your MIDI controller.  The incoming MIDI     message is assigned to all cells that are in MIDI Learn mode.

         Tip: You can put multiple cells on different rows into MIDI Learn mode, and all cells               will be triggered by the same MIDI event.

    The MIDI message is assigned to a specific cell in the grid, not to any particular pattern or     loop. You can even use MIDI Learn on empty cells.

    After a cell has been assigned to a MIDI message, you can press the corresponding key,     pad or button on your MIDI controller to trigger the cell.

         1. Make sure the Cell MIDI Trigger button in the Matrix view toolbar is enabled.

         2. Press the desired key, pad or button on your MIDI controller.  All cells that are               assigned to the incoming MIDI message will be triggered.

Sorry for the ugly formatting but it looked swell before posting.

OK, I finally got it going.

After I hard rebooted, both of the control surfaces worked as described.

Whether or not I can get my friend to trigger each section (8 instruments, not including the vox) on time is another story.  It still has to be easier on him than actually playing each note on the bass (keyboard) and still actually sounding somewhat like a live band.

EDIT:  Removed ABCP remark.  Sorry :-) .

Thanks, PenguiN42.  I try it with something else as I too was experiencing some less than stellar results.