Making you swf scaleble

Hi

I have a .as class file with hard coding and scaleble.

When I place a mc on the stage and publish my swf

1.  I can see the mc if it is coded like this: this.x = 600; //the page width it 1200

if I replace if with scalable code

2.  I can not see : this.x = (stage.stageWidth-this.width)/2;

Why does #2 not work?

Thanks

Charine

Here is the complete file:

package 

{

    import flash.display.MovieClip;

    import flash.text.TextField;

    import flash.events.Event;   

    public class wordText extends MovieClip

    {

        public function wordText()

        {

            this.x = 642;

            //this.x = (stage.stageWidth-this.width)/2;     //does not work when I uncomment it

            this.y = 743;

        }

    }

}