Trouble with a dropdown menu on a web page (Watir?)

I’m trying to select two items in two dropdown menus that are
semi-connected in the page.

When you select an option on the first menu it changes the options in
the second menu. The problem is that when I directly send the selection
in the first menu, like:

ie.select_list(:name, “form-sub-main”).select “Hamburger”

The second menu doesn’t change. It stays blank as though I had never
selected anything, so I can’t send the next command to the second menu.

Any ideas? I thought I would send keystrokes to the first menu or
something as that always works, but I don’t know the syntax to set that
up.

Thanks,

N