Lars asks them to next to a shoulder fore with no bend making sure it not hindquarters out. They come to the walk and establish the connection  and then go back to the exercise. When she loses the base of the neck she halts to reestablish it, and Lars encourages her to eventually do it through coming to the walk, then in the half halt.  She is able to reestablish it in the trot so they try again in the canter.