It sounds like your training is inconsistent.
You are either not rewarding enough or not rewarding at the right time.
Stop everything and give her a break (vacation from all training for about 1 week) then re-train using a clicker.
http://www.youtube.com/watch?v=_wv1u...feature=relmfu -great video.
I see this alot with clients who reward at the wrong time, or not rewarding enough. The dog is confused.
Keep everything the same, the verbal commands and hand signals.