Why won't my scene load?

Hey everyone, I'm very new to Unity and programming. I followed a tutorial online and I'm recreating a pong style game. I created a "game over" scene, and I set up a triggerable box collider that for text that says "Play Again". When the user clicks "play again" (the box collider) I am using this JavaScript:

private var ray : Ray; private var rayCastHit : RaycastHit;

function Update () {
if(Input.GetMouseButtonDown(0)) { ray = Camera.main.ScreenPointToRay (Input.mousePosition);

     if(Physics.Raycast (ray, rayCastHit))
     {
         if(rayCastHit.transform.name == "Play_Again_Button")
         {
             Application.LoadLevel("Main_Pong_Game");
         }
     }
 }

}

Does anyone know why this wouldn't work? The scene(s) have been added to the build in build settings. Thanks, Adam