Finding out when an internal movie clip is loaded?

Alright I’ve got about 3 days of flash experience under my belt and I might be missing something obvious… so here I go:

I’ve got an Array that I use to build a menu using attachMovieClip (I used http://www.kirupa.com/developer/actionscript/xml_dropdown_menu.htm as a reference) The actual list is inside of it’s own movie clip and it loads and works perfectly.

What I’m actually trying to accomplish, though, is… how can I (from the parent movie) tell when it’s loaded and call it’s methods to add or remove items from the list. It seems like when I do… the methods don’t exist which I take to mean that the movie isn’t done loading internally. Is there a way to know when internal MCs are done loading?