Array out of range

Error:

 IndexOutOfRangeException: Array index is out of range.
 RespawnMonster+$Start$151+$.MoveNext () (at Assets/ActionRPGKit/Script/RespawnMonster.js:10)

Script:

 #pragma strict
 var enemy : Transform;
 //var point = 10;
 var pointName : String = "SpawnPoint";
 var delay : float = 3.0;
 var randomPoint : float = 10.0;
 
 function Start () {
     var spawnpoints : GameObject[] = GameObject.FindGameObjectsWithTag (pointName);
     var spawnpoint : Transform = spawnpoints[Random.Range(0, spawnpoints.length)].transform;
     
     yield WaitForSeconds (delay);
     var ranPos : Vector3 = spawnpoint.position; //Slightly Random x y position from respawn point.
     ranPos.x += Random.Range(0.0,randomPoint);
     ranPos.z += Random.Range(0.0,randomPoint);
     Instantiate(enemy, ranPos , spawnpoint.rotation);
     Destroy (gameObject, 1);
 }

I'm lost...