Drop down menus?

Hi,

I have been struggling for a while to figure out issue but i need to work out why the drop down menus aren't working in the main menu at the top of my garland theme.

I was hoping for the 'children' to pop out in a style that was coherent with the Garland theme although i was very dissapointed when nothing happened.

so i was wondering how i could fix this issue and have a drop down menu appear in the main menu at the top right of the garland theme with those triangles?

i looked into nice menus and DHTML menu but it doesn't seem to work as the main menu is not a registered region in Garland.