Adobe Flash - Error, "Access of Undefined Property"

/* Stop at This Frame

The Flash timeline will stop/pause at the frame where you insert this code.

Can also be used to stop/pause the timeline of movieclips.

*/

stop()

/* Mouse Click Event

Clicking on the specified symbol instance executes a function in which you can add your own custom code.

Instructions:

1. Add your custom code on a new line after the line that says "// Start your custom code" below.

The code will execute when the symbol instance is clicked.

*/

MainMenu.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler_100);

function fl_MouseClickHandler_100(event:MouseEvent):void

{

  gotoAndStop(1);

}

/* Mouse Click Event

Clicking on the specified symbol instance executes a function in which you can add your own custom code.

Instructions:

1. Add your custom code on a new line after the line that says "// Start your custom code" below.

The code will execute when the symbol instance is clicked.

*/

Song_1.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler_101);

function fl_MouseClickHandler_101(event:MouseEvent):void

{

  fscommand("exec", "Song_1.app");

}