1. I found out why. Every time unit is equal to "player". action is always equal to "HEAL" so the following if statement never passes: if unit == "player" and action ~= "HEAL". Did this testing on the target dummies.

    What changes do I need to make this work?


    You are misunderstanding what CombatTracker does. It tracks INCOMING damage, not the damage you are doing to someone else. In order for it to do anything other than return 0, you need to be hit by something. Tracking outgoing damage is more difficult, but that's covered in the chapter on the combat log. Hope that makes sense.