How to pass variables from .fla file to .as file in as3

kglad​ Main is already document class and I extend to MovieClip class.

the code is like this:

test.fls:

    import Main;

    var my_var;

    stage.addEventListener(MouseEvent.CLICK, onLoaded);

    function onLoaded(e:Event):void

     {

       my_var = "Maziar";

       //trace(my_var);

     }

Main.as

package

    {

      import flash.display.Sprite;

      import flash.geom.Point;

      import flash.events.MouseEvent;

      import flash.utils.Timer;

      import flash.events.TimerEvent;

      import flash.events.Event;

      import flash.display.MovieClip;

      public class Main extends MovieCLip

     {

       public function Main()

      {

        if (stage)

        {

          init();

        }

        else

       {

        addEventListener(Event.ADDED_TO_STAGE, init);

      }

      addEventListener(Event.ENTER_FRAME, waitForMyVar);

     }

     private function waitForMyVar(e:Event):void

     {

       if (my_var != null)

       {

         trace(my_var);

         removeEventListener(Event.ENTER_FRAME, waitForMyVar);

        }

      }

   private function init(e:Event = null):void

  {

    removeEventListener(Event.ADDED_TO_STAGE, init);

  }

     ...

}

}

I still get the errors "error: 1120: Access of undefined property my_var".

the error is in line: if (my_var != null) and line : trace(my_var);