"Command" pulldown menu doesn't work

When I open a latex document in emacs, the auctex menu and toolbar 
appear as expected. I can use my mouse (a Synaptics touchpad) to reveal 
the pulldown menus for the categories "file," "latex" and so forth. The 
only exception is the category "command." When I double-tap on 
"command," nothing happens.

I'm running emacs 21.4 and auctex 11.54 on gentoo linux. (I'm aware that 
there's an auctex 11.55, but 11.54 is the latest version in gentoo's 
"portage" system; in any event, at one point I tried hand installing 
11.55 and had the same problem.)

I saw a reference in the release notes about a problem with an earlier 
version of auctex not being able to recognize the appropriate commands. 
I don't think that's the problem in my case because I can execute the 
commands when I access the menu through the F10 key. (That also leads me 
to believe the problem is not a result of the way I've set up 
permissions on my system; that is a possibility though, since I'm fairly 
new to linux and indeed to emacs as well.)

This is a fairly minor annoyance, but I would appreciate any pointers on 
where the problem may lie.