Its probably a bug in the MB concerning private forums. They are probably just filtering out all private forums on the drop down and not checking to see it you have access or not.
Well, actually it might be my fault. The board admin section does not support assigning specifc permissions to users, you can only assign users to groups. Since that would be too restricting for the we we have this forum setup, I wrote a program so JC can get around this limitation and assign form permissions to people directly.
The problem described probably wont get fixed unless they add the feature I added to V3.0 of the board, which is due out soon.