Do the "kill self" last. Once you kill self (the actor running the behavior), the behavior stops processing so you never get to add points.
Personally, I would put this on the Player actor, and look for a collision with a special "Coins" collision group instead. You can still kill the coin from itself separately, but since the score is something that belongs to the Player (I imagine it should anyway), it's easier to modify from a behavior attached to the player.