AS3 HELP Movieclip inside of a Movieclip with code

So i’m trying to create an accordian menu that is xml driven. I’m only starting with the nav right now, and it’s pretty basic. I’m having trouble getting a movieclip inside of another movieclip with code. I’m getting this error (ReferenceError: Error #1069). I have two movieclips in the library, and both of them are linked for action script. I know that i need a main movieclip, and a sub movieclip that gets called and activated when the main movie clip is clicked on. I’m not sure how to activate it, or how to place a MC inside of another MC with code. If anyone would like to take a stab at it that would be awesome.