stage.stageWidth and stage.stageHeight Issues

For one of my recent projects I was running in to an issue where my stage dimensions were equal to 0 (zero). This was only occuring when I was referencing the dimensions within a class file that was not within my document class. The only fix that I have found was the need to add an event listener ADDED_TO_STAGE to the class file.

My class file looked like:

package {
	import flash.display.Sprite;
	import flash.events.Event;

    public class MyClass extends MovieClip {
		public function MyClass()
		{
			addEventListener ( Event.ADDED_TO_STAGE , init );
        }

		private function init(e:Event):void
		{
			trace ( "Stage Width: " +  stage.stageWidth + " -> Stage Height: " + stage.stageHeight );
		}
    }
}