Does not work: @script RequireComponent(AudioSource)

Hi,

I´m going through the Unity Game Dev Essentials and have a little problem with the

@script RequireComponent(AudioSource)

command. It simply doesn´t work.

It should add an audio source component to the object I add this script to, but it doesnt´t.

In chapter 8 there is this simple script:

 var levelToLoad : String;
 var normalTexture : Texture2D;
 var rollOverTexture : Texture2D;
 var beep : AudioClip;
 
 function OnMouseEnter(){
     guiTexture.texture = rollOverTexture;
 }
 
 function OnMouseExit(){
     guiTexture.texture = normalTexture;
 }
 
 function OnMouseUp(){
     audio.PlayOneShot(beep);
     yield new WaitForSeconds(0.35);
     Application.LoadLevel(levelToLoad);
 }
 
 @script RequireComponent(AudioSource)

Anyone knows what could cause it not to appear in the Inspector ? :(

Thanks in advance for any help !