have you restarted either X or the panel? in Gnome, and I guess in KDE too, some changes need that you restart the panel. if you use gnome, simply open up a terminal and give a command:
and it should be closed and then reloaded. try if that fixes the problem...or if you're not a Gnome user, and don't know how to reload the panel/menu, log out and log in.
if that won't help either, you can add it manually...at least in gnome you can open the menu, then a submenu, say Internet, and right-click that menu - then choose "Entire menu > Add new item to this menu" and there you are.. I guess it works somehow the same way in KDE? I'm not sure though..