User blogs end up being a theme I dont have installed.

When I create a test user blog the theme ends up being a theme that isnt installed under my directory. I have on the same HOst Gator account and the new user blogs end up using the theme even though it isnt isntalled under WPMU on my

Any idea how to fix this? Maybe I just dont have the setting for which theme to use set correctly? How do I set which theme(only want to use one)each user blog is? It will be a seperate blog from my main page blog. is the main blog and you can see on it is using the theme of

Thanks all!