I see my active theme, then under it I see available themes - and one theme plain 2.0. The plain 2.0 theme has a side bar with lots of widgets in it. It lets me customize this theme and preview it - however - when I save it - it will not let me activate it.

I added a text widget - and moved it to the top of the sidebar - that's about it. Still it won't activate. What's up?