As I wrote above, in Joomla 1.5 you have to setup the ranks in Menu manager.
So on the backend go to Menus menu, and select the menu where you have the roaster (e.g. Mainmenu). Click on Roster (maybe it’s called something else, sorry I really don’t know how your menu item called), and on the right side click on “Parameters (Component)”. Enter the ranks there.