AU instruments(omnisphere, kontact, etc...) not showing up in mainstage?

I recently had a problem with my computer and had to reboot the harddrive. I was using several virtual instruments such as omnisphere on mainstage without a problem. But now I can't figure out how to get mainstage to use them. I've tried using audio unit manager several times. They just won't show up in the au instrument list. How can I fix this?