Yes, SHE knows the commands, but you need to learn how to effectively give them, and WHEN to effectively give them. I'm a trainer, and I see this all the time.

I am pretty bad about typing answers to common problems like this one, because finding out what you're doing wrong requires face to face dialog. Its even best to see how you interact with your puppy. Thats where a trainer helps you, because you are doing something wrong, you just aren't aware of it... and what you're doing wrong isn't earthshattering or even "wrong" its just not getting through to the puppy. A trainer would point it out in one second -- is it your voice tone? Your body language? Your timing? A trainer right there with you will figure it out in five minutes. Its all things I can't do over the internet.