Cannot have access to stage in document class

Just tried using cs5 on my new macbook and I have a tlf text object on the stage with an instance name of mText. I tried to access (mText.text = “test”) it like this and got a null object reference. I tried to trace the stage from my document class and it was null when the tlftextbox was on the stage but i could trace stage correctly when I deleted the textbox. Please help and thanks

package  {

	import flash.display.MovieClip;
	import flashx.textLayout.elements.TextFlow;

	public class WriteCode extends MovieClip{

		public function WriteCode() {