I have a TB he was pastured with from the time I got him, they were in a small dirt lot most of the time and I got into the habit of free lunging both of them. Fox (my 3 year old) began following my TB through the gaits, he learned that the 'cluck' means trot and 'kiss' means canter. I moved them to a barn that had a round pen, I used that for a few months without the line, first with them together and then on his own and he did well, only threw a buck a few times and I drove him through it and he got really good about not bucking when he was working.
When I was finally able to move them to my own property I lost the use of the round pen so I recently have started bringing him out on the line, I've only got him out twice on it, the first time went well, he trotted slowly and pulled outward a few times but we ended with one full, complete circle with no fulling outward.
The second time is when I ran into problems, I lunged him and he went well at first till he tried eating the grass and I flipped the whip and he bucked, I just thought that I freaking him out a bit so I pulled him back in and asked him to trot on, holding the whip out behind him and my shoulders at his rump to keep him forward. Eventually I had to stop because he would not trot on without the whip which seemed to make him buck.
Any suggestions? I plan on getting a video later today and post it so people can see whats going on... it's very possible its all me, but I can't pinpoint it.