Nullreference exception after build!

This Script works in the game engine, but after I build the game, it won’t work!

var enemyprojectile : Rigidbody;

var speed = 10;

var enemy : Transform;

var shotS : AudioClip;

function Start() {
var rendum = Random.Range(1F,3F);
InvokeRepeating(“Shuut”, 2, rendum);
}

function Update() {
transform.LookAt(enemy);
}

function Shuut () {

audio.PlayOneShot(shotS);

clone = Instantiate(enemyprojectile, transform.position, transform.rotation);
clone.velocity = transform.TransformDirection( Vector3 (0, 0, speed));

Destroy (clone.gameObject, 5);
}

Please help

-DC

The null reference is generally linked to a missing variable - a null variable

did you assign ennemy in the inspector? and did it save that assignment?
you may need to change to:
var enemy : GameObject;

then use
transform.LookAt(enemy.transform);

did you assign the audio clip and did it save it?

if in play mode it will not save it.
hope that helps,