the reason she isnt excited could be genetic or it could be you. its hard to say over an internet forum.
you have to act silly and praise praise praise. IF you are doing a good job then let your pup mature a little bit. my dogs ball drive didnt kick in until 6 months. it was like i got a new dog in terms of intensity and focus. right now i'd stop "training" and just play with your dog. make your dog think you are the most fun thing in the world.