Once we step in the ring and the leash comes off, my dog acts like she's never heeled in her life. She whines and won't pay attention in the ring, do you have any suggestions?

I have a 3 year all black German shepherd that I am training for competition obedience. We have a CD and am working on her CDX. However, I am having problems with her and hope you can give me some insight. I have always trained with food and toys. She has high drive but is very soft and she is a whiner. When we are training, we have no problems. It's when we step into the ring, and the leash comes off. When we are training and does not have a leash on she heals beautiful. But once we cross over into that ring she acts is if she never healed in her life, constantly whines and has never "heard" the attention word. (We do practice in ring situations to.) I just cannot get that crossover from training to into the ring. Can you please help me. She is really a beautiful dog and has great drive and great potential and she enjoys working. Is there any help? Thank You