Oh. You know, I'm being stupid. The forum blocks normally only ever show up on the forumhome page, so this doesn't make any sense unless you have a mod that allows the sidebar on other pages. I think there is more than one mod that does that though.
Sorry, I guess ForceHSS's suggestion was right and I just wasted your time.
Edit: Here's one:
www.vbulletin.org/forum/showthread.php?t=233871 and that one seems to have an option for displaying block only on certain forums, so you don't need to do the template thing I suggested.