AS2 Problème avec _lockroot !!!

import mx.transitions.Tween;
import mx.transitions.easing.*;

var myShowXML = new XML();
myShowXML.ignoreWhite = true;
myShowXML.load("slideshow.xml");

myShowXML.onLoad = function() {
	_root.myWidth = myShowXML.firstChild.attributes.width;
	_root.myHeight = myShowXML.firstChild.attributes.height;
	_root.mySpeed = myShowXML.firstChild.attributes.speed;

	_root.myImages = myShowXML.firstChild.childNodes;
	_root.myImagesNo = myImages.length;

	createContainer();
	callImages();

};


function createContainer() {
	_root.createEmptyMovieClip("myContainer_mc",1);

	myContainer_mc.lineStyle(5,0x000000,100);
	myContainer_mc.lineTo(_root.myWidth,0);
	myContainer_mc.lineTo(_root.myWidth,_root.myHeight);
	myContainer_mc.lineTo(0,_root.myHeight);
	myContainer_mc.lineTo(0,0);

	myContainer_mc._x = (Stage.width-myContainer_mc._width)/2;
	myContainer_mc._y = (Stage.height-myContainer_mc._height)/2;

}

function callImages() {

	_root.myMCL = new MovieClipLoader();
	_root.myPreloader = new Object();
	_root.myMCL.addListener(_root.myPreloader);

	_root.myClips_array = [];

	_root.myPreloader.onLoadStart = function(target) {

		_root.createTextField("myText_txt",_root.getNextHighestDepth(),0,0,100,20);
		_root.myText_txt._x = (Stage.width-_root.myText_txt._width)/2;
		_root.myText_txt._y = (Stage.height-_root.myText_txt._height)/2;
		_root.myText_txt.autoSize = "center";

		_root.myText_txt.text = "test";

	};

	_root.myPreloader.onLoadProgress = function(target) {

		_root.myText_txt.text = "Loading.. "+_root.myClips_array.length+"/"+_root.myImagesNo+" Completed";

	};


	_root.myPreloader.onLoadComplete = function(target) {

		_root.myClips_array.push(target);
		target._alpha = 0;

		if (_root.myClips_array.length == _root.myImagesNo) {

			_root.myText_txt._y = myContainer_mc._y + myContainer_mc._height;
			_root.target_mc = -1;
			moveSlide();
			myShowInt = setInterval(moveSlide, (_root.mySpeed*1000)+1000);


		}

	};

	for (i=0; i<_root.myImagesNo; i++) {

		temp_url = _root.myImages[i].attributes.url;
		temp_mc = myContainer_mc.createEmptyMovieClip(i, myContainer_mc.getNextHighestDepth());

		_root.myMCL.loadClip(temp_url,temp_mc);
	}

}


function moveSlide() {

	current_mc = _root.myClips_array[_root.target_mc];
	new Tween(current_mc, "_alpha", Strong.easeOut, 100, 0, 1, true);

	_root.target_mc++;

	if (_root.target_mc>=_root.myImagesNo) {
		_root.target_mc = 0;
	}
	
	_root.myText_txt.text = _root.myImages[target_mc].attributes.title;
	next_mc = _root.myClips_array[_root.target_mc];
	new Tween(next_mc, "_alpha", Strong.easeOut, 0, 100, 1, true);

}