One of the people in my group lesson rides a black draft mix named Ronan. We usually warmup on small jumps. Ronan usually goes first. He keeps refusing jumps. Kate, Ronans rider, does back and fourth movements with her hands but they still don't work. It is dangerous for Kate, Ronan, Jack and I, plus all the other riders and their horses they ride. Any tips for helping control the refusals? Help us out!