Show Slide In on BuddyPress Group Forums

Team WPMU,

I'm looking for a way to prompt users to join my site when they land on a forum page. Slide In looks to be a great solution to this, as I can select it to show on Forum, Topic, or Reply pages.

However, it doesn't seem to show when a non-logged in user is on a BuddyPress Group Forum topic page (as opposed to the straight up bbPress forum index pages) -- is there something specific I need to do to make that happen?

Thanks!