I am also having the same problem, but 3.2. I had problems making new forums and getting them to show up (I eventually succeeded) and now the styles are not registering as uninstalled. I have uploaded them to the styles folder on my forums, the files of the styles in folders with their names on them.
Here is the complete thing...
which has /template and /theme, as well as style.cfg and an images folder. There are two others with the same set up. None of them are showing up as on the server WTH!!!