Operant condition dog experiment

My experiment was that I wanted to train my one year old black lab to shake hands. Her reward for this would be a dog cookie. I would give her one twice a day. First, I would have her sit, which she is trained to do, then I would say "shake". If she didn't do it, then I would pick up her right front paw and say the word "shake". Then i put it down and try it again. If she doesn't do it the second time, I pick up her paw again and say shake and actually do the motion and then give her the cookie so she knows she gets rewarded for shaking. I would also use my older dog who is trained to do it. I have my older dog shake first so she sets an example. I have tried since friday to get her to do this. We have had no success but I know were getting close. The environment is my kitchen without any body else in it so she doesn't get distracted. The behavior is shaking my hand. The reinforcemnt is the cookie and also praise for doing this task. I know if i keep working at it, eventually i will see success. I know I am close because her behavior when I tell her this changes from hyper to clam. Also I notice she shifts her weight to one side as if she was raising a paw. These characteristics are very similar to my older dog.       Jacob Chernesky