can some1 help get my dynamic menu working?

positionNav = function(){
//loops through the total number of main navigation elemnts
	for(i=0;i<mainNav;i++){
//creates a variable that tells the height and Y of each main navigation button, and sets the next one
		var nextY = navigation_mc["button"+(i-1)+"_mc"]._y + navigation_mc["button"+(i-1)+"_mc"]._height;
		navigation_mc["button"+i+"_mc"]._y = nextY;
	}
}
makeSubNav = function(obj,c){
//when you press a main nav, this gets called
//it attaches the same button, but moves it and positions it so that it looks like a sub nav
	for(i=0;i<c;i++){
		obj.attachMovie("buttonID","sub"+i,depth++);
		obj["sub"+i]._x = obj._x + 10;
		obj["sub"+i]._y = 16*i + 16;
		obj["sub"+i].label_txt.text = "sub element " + i;
	}
//notice that after we create this subnav, we have to reposition according to the new height (that the sub nav added)
	positionNav();
}
killSubNav = function(obj,c){
//remove the sub nav as easily as we created it
	for(i=0;i<c;i++){
		obj["sub"+i].removeMovieClip();
	}
	positionNav();
}
//total nav items
mainNav = 10;
//create a navigation movieclip, so that it's all in one place to handle
this.createEmptyMovieClip("navigation_mc",depth++);
for(i=0;i<mainNav;i++){
//attach
	navigation_mc.attachMovie("buttonID","button"+i+"_mc",depth++);
//set this open variable.  This is used when i create and uncreate the sub nav.
//it starts as positive, so it tells me that a subnav doesn't exist
	navigation_mc["button"+i+"_mc"].open = 1;
// this i value is used to dymically lable my buttons text fields
	navigation_mc["button"+i+"_mc"].i = i;
//position it
	navigation_mc["button"+i+"_mc"]._y = 16*i;
//set the nav text
	navigation_mc["button"+i+"_mc"].label_txt.text = "Nav element " + i;
//tell the button to create a sub nav if it's not open, and to delete it if it's open
	navigation_mc["button"+i+"_mc"].nav_btn.onRelease = function(){
		this._parent.open *= -1;
		if(this._parent.open < 0){
			makeSubNav(this._parent,this._parent.i);
		} else {
			killSubNav(this._parent,this._parent.i);
		}
	}
}
//position the nav so it all looks right
positionNav();