Menu Two - Only Shows Top Layer

I created a site with a theme that uses two menus (Custom Community 1.0 which is being upgraded so I swapped to BuddyPress Fun - which is the only WPMU Dev theme - it appears - that has two menus.

The trouble is - the sub-menus at the top of the page DO NOT SHOW. They show for the main menu - just not for the top (second) menu).

Why is that? There goes a significant portion of my site's content that is now not accessible.

Help to get them to show please would be appreciated.

(Also I have no idea how to add to a thread - have emailed and I can see that other people can add more info to a thread, but I cannot see how to do it and have searched on the site and sent a question about it.)

Thanks in advance for any resolution.