Audio not playing!

Here is the code:

 var Cool = false;
 var CanHit = true;
 private var AtBase = false;
 private var hits = 0;
 var die : AudioClip;
 var helth = 20;
 
 
 var Bullet : Transform;
 
 function Update () {
 
     if(AtBase == false) {
     
         transform.Translate(0, 0, .04);
     }
 
 }
 function OnTriggerEnter( other : Collider) {
     if(CanHit == true) {
     if(hits == helth) {
         CanHit = false;    
         print("I AM DEAD");
         audio.clip = die;
         audio.Play();
         yield WaitForSeconds(3);
         Destroy(gameObject);
     }
     }
     if(CanHit == true) {
     print("Hit");
     hits += 1;
     }
 }

The Audio was playing just fine then it was not working and i got a error when i built the game dont know if that has to do with some thing