Looks like you are checking a hit event on the cube against another actor and seeing if that actor implements the interface. But in your drawing it looks like the cube hits the “ground” and unless the ground is an actor that implements the interface this would do nothing. If your second cube fell on the first cube then the first cube would execute its interface. Also who is the “mover” BP? this is a confusing set-up that I don’t think is doing what you think it should. I think your hit events are backwards.