Problem in class

I want to use a variable that i have defined it in my class in onEnterFrame condition in a function in same class , but when i trace it , i face with undefined .
is there anyone can help me? if you know how to do this ,please correct the attached file and uploade it here , thank you so much

class Harekat extends MovieClip {
	private var myVar:String="Hello";
	public function Shetab():Void {
		_root.onEnterFrame = function() {
			trace(myVar); // output is undefined