First, try doing the trick with a dead yo-yo. That way you can practice the movements without having to worry about the yo-yo spinning out on you.
Second, are you moving your legs correctly? If you’re right handed, you start off with your right leg in front of your left, and end with your left leg in front. The opposite occurs when you’re left handed.
Also, what part of the the trick are you specifically having problems with? Can you maybe give us a reference point in this video? http://www.youtube.com/watch?v=xg13L73K8Ig