I think I know what causes this. The AI has a "target selection" function that runs and returns the best target for adrenaline. It uses adrenaline. Then, when it comes to using adrenaline again, it runs the target selection function again with - obviously - the same result. Now a conditional kicks in, which probably says something like "if the target has already got adrenaline, don't waste it! It's not cumulable!", which nulls the action, and the adrenalines sit useless in the AI hand. To fix that, you would need to kill the conditional and add a conditional in target selection which cuts potential targets based on who already has Adrenaline on.
Of course, that's kind of a shot in the air, since I didn't actually see the code. But I get a feeling that the problem is something like that. .-. Dunno why I posted it here, though. Whatever, ignore me.