I have really been trying to make sure I am giving him exact arm placement being straight up for backs and 45degree for angle backs and hand at waste level for overs. I can do backs and angle and he is fine, angle and over and he is fine. Mix them all together randomly he starts taking an over for a right angle back. this is all done on a half wagon wheel remote sit bumpers about 20 yds away I am 10yds from dog. he knows where the piles are. used some white poles that helped a little. I have done this drill a lot, any advice?