Need help mapping APC40 to remix deck in traktor

I am currently working on a remix deck mapping for the apc40. My goal is to use the ddj-t1 to control 3 track decks and the apc40 to control 1 remix deck. The problem I am having lies in the mapping of the leds. The way I have it mapped now (a very simple way) has the led color of choice lit all the time. What I would like is for the button to be off when no sample is loaded in the cell. Then when a sample is loaded in the cell, the button lights up. Another way to put this is how do I control led function by the action of loading a sample? Seems very similar to hot cue buttons. Most people have them set to one color when no hot cue is stored and another color when there is a hot cue stored. That is what I am going for but with samples in a remix deck. I am new at this mapping thing, and i know there is probably a very simple solution (maybe with modifiers, etc). Any help would be greatly appreciated!