I am trying to teach eero some tricks, and he's got many of the basics down (sit, stand, down, leave it, drop it, etc.) but he can't seem to get roll over. I usually tell him to go down and then start moving his treat up near his side to try to get him to follow but it just doesn't seem to work. Any advice? Also "bang" is *the* most amazing trick I've ever seen! I want eero to learn that!