It's a Drenalin. I had this problem with the bow I used before that, but not at first. I will draw back and while holding and aiming the string will jerk forward, and I think it is a matter of not hitting the back wall (too long of a draw length).

This weekend I am getting the string adjusted so it shortens my draw length a half of an inch. If that doesn't work, I will need a different cam allowing it be shortened even more. Hopefully that will do the trick.

I am alsousing a new release. The old one had a broken strap, so I just replaced it. I'm not happy with it and I'm going to try out a couple more while getting the draw length adjusted.