Trouble with Primary Menus / Child Menu Items

Hi there,

here's one I've been beating my head against for a few days, probably there's a simple solution.

My primary menu is at the top of the page, and I have a bunch of primary menu items, call them

A B C D E

each of which links to a node.

I want to have each of these have dependent child submenus that open up when you click on a primary menu item, so

A -> a1, a2, a3
B -> b1, b2, b3, etc.

So that when you click on A, you see

A B C D E
a1 a2 a3

and when you click on B, you see

A B C D E
b1 b2 b3

I don't want to put the menus in blocks at the side; I am just playing with the Garland theme. I've gone to build->menus->settings and have all three options set to "primary links", and I have defined the Primary Links menu with members A, B, C, D, E, and each of these has child items a1, a2, a3 or b1, b2, b3 respectively. However, the child menus never show up at the top.

The help text in build->menus->settings says, "Select what should be displayed as the secondary links. You can choose the same menu for secondary links as for primary links (currently Primary links). If you do this, the children of the active primary menu link will be displayed as secondary links." which is exactly what I'm trying to do.

Also, if I set "Source for the secondary links: " to another menu that has members, that will display nicely, but won't change depending on which of the primary links I've clicked on.

What am I doing wrong? I don't want pulldowns or anything fancy.

-edit:- I am trying to do this: http://drupal.org/node/525568 -- is there a way to do it without an additional module? The above description makes it sound like it should be possible from the base install...Also, I've tried this with numerous themes (Garland, Chamaeleon, etc.)