Hello: I am working with an 11 month old border collie who is doing pretty well on the starting dogs exercises. My question is: when I am working the “follow his tail/back off” exercise, he does not follow the sheep toward me or bring the sheep to me. Is this a factor of his age? Or is there something I should do to assist? He is happy to flank, work the cones and lie down. But when there is distance between me and him and the sheep are his to move, he lies down and won’t come forward. Thanks.