Errors with stageWidth/stageHeight in package

hello everyone, I’m trying to make a class that will scale a clip when the stage resizes. I have the Stage resize set to NO_SCALE so the majority of clips on the stage will not scale, however i want to make an exception. So i wrote the package below. However, when i try to run the movie, it throws this error:

1119: Access of possibly undefined property stageWidth through a reference with static type Class.

Obviously i’m missing something and need some help. Thanks in advance.

package bmilesp.display.LayoutTools {

import flash.display.Stage;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import flash.display.MovieClip;

public class LayoutTools {
    private var _stageOriginalWidth:Number = Stage.stageWidth;
    private var _stageOriginalHeight:Number = Stage.stageHeight;

    public function scaleWithStage(my_clip:MovieClip):void{
        var scaleChangeWidth:Number = Stage.stageWidth/_stageOriginalWidth;
        var scaleChangeHeight:Number = Stage.stageHeight/_stageOriginalHeight;
        my_clip.width = my_clip.width * scaleChangeWidth;
        my_clip.height = my_clip.height * scaleChangeHeight;