wpmu-nelo nav menu (sub-sub-pages)

I have a site with pages, sub-pages, and sub-sub-pages.

Using wpmu-nelo, I would like the nav menu (in the header) to show the pages (which it does) and the subpages (which it does–in a drop-down list beneath each page), and also the sub-sub-pages. I can’t seem to get it to do that.

If I very very carefully roll my cursor down the drop-down list of sub-pages, I can see (after changing wp_list_pages to depth=0 in header.php) that there ARE links to the sub-sub-pages (I can see the sub-sub-page in the status bar at the bottom of my browser window). They are just invisible–no text or link shows up, although the cursor does change when you manage to hit them just right.

It seems like this should be an easy CSS fix (ideally, I would like them to be indented slightly–“nested”–beneath their parent pages in the drop-down, maybe with a raquo or two–even a dash, but any solution that allows them to appear would be fine).

Any ideas?