Enemy don`t play dead!

//i put this script on my enemy behaviour... but animation don`t play "dead"... what`s wrong???? my enemy take the damage from prefab "bullet" //

var health=3;

function TakeDamage(damage:int)

{

health --;

if(health <- 0)

{

    Die();

 }

}

function Die () {

   animation.Play("dead");

   yield WaitForSeconds(2);

   Destroy(gameObject);

}