IndexOutOfRangeException: Array index is out of range.

i have a big problem.. i am scripting the networking for my online game, and i stutterd op to this bug. this is the NetworkManager script. but my player can't spawn because of this anoying bug:

void OnGUI() { if(MatchStarted == true && !MyPlayer.IsAlive) { if(GUI.Button(new Rect(0,0,50,20),"Spawn")) {

             int SpawnIndex = Random.Range(0, LevelManager.ins.SpawnPoints.Length -1);
     ERROR>>>>>>         MyPlayer.Manager.FirstPerson.localPosition = LevelManager.ins.SpawnPoints[SpawnIndex].transform.position;
             MyPlayer.Manager.FirstPerson.localRotation = LevelManager.ins.SpawnPoints[SpawnIndex].transform.rotation; 
             MyPlayer.Manager.networkView.RPC("Spawn",RPCMode.All);
         }
     }
 }

}

can someone help finding the bug i have?? thank you

ps the error is on the lane where "error>>>>>" stands