Error Message When Using a Class Files to Control Navigation

This is my first attempt at using a class file in a flash project. My intent is to keep all of my navigation elements in class file called "Navigation".  However, I keep getting an error message when I publish.

I am using a button to go back to the main screen and I gave that button the instance name of "bnt_home". I have also linked that button in the library to the class "Navigation".

Here is the code:

package

{

    import flash.display.SimpleButton;

    public class Navigation extends SimpleButton

    {

        public function Navigation()

        {

            bnt_home.addEventListener(MouseEvent.MOUSE_DOWN, goNavigation);

        }

        private function goNavigation(event:MouseEvent):void

        {

            gotoAndPlay(1,"Main");

        }

    }

}