Yes, try to remember that she's just a baby, and if it's not FUN, you won't be able to keep her interested. If you're just standing there holding the treat and saying "down" in a flat stern voice, she has probably gotten bored with the game. I use a high pitched voice, and move around and make a big deal when they follow through with the command. Treat, praise, rubs when they complete the command. Moving around keeps her attention on you and interest on what you're doing. Extra praise adds more incentive to the game. Some dogs need more to get them going.