ActionScript 3.0 :: Stage.stageWidth And Height Not Working: 1009

I've decided to start re-writing my project, but this time making the use of class files rather than nesting code inside my MovieClips.

Now it's come to the "message box" that I previously wrote, and I'm having some troubles. (note: I don't really want to download a pre-built one as my message box class end up being the backbone for several custom interfaces).The problem is that I cannot, for the life of me, figure out why my message box class cannot access "stage.stageWidth", "stage.stageHeight", "MovieClip(root).currentWidth", etc.

This is the code for the working "messageBox.as":

ActionScript Code:
package com.components{
import flash.display.Shape;
import flash.display.MovieClip;

[code]....

I've tried several variations of creating the movie clip, but to no avail. I've tried like creating a global movie clip variable and that attatching the movieclip to it in this function, the same with a display object, creating a function variable and doing both of the above, etc.I just cannot figure it out! All of my other classes are working just fine!