ai spawning please help

there something with my ai spawner pretty much this is for waves but im not sure its not working im attached it to a game object and nothings working its saying its all mest up heres the script

 #pragma strict
 
 var spawnPionts : Transform[];
 var enemyPrefabs : GameObject[];
 
 var yieldTimeMin = 2;
 var yieldTimeMax = 5;
 
 static var enemyCounter = 0;
 
 var spawnXOffsetMin = 0;
 var spawnXOffsetMax = 0;
 
 var spawnZOffsetMin = 0;
 var spawnZOffsetMax = 0;
 
 var spawnYOffsetMin = 0;
 var spawnYOffsetMax = 0;
 
 var defaultSpawnNumber = 3;
 
 var waveNumber = 1;
 
 var isSpawning = false;
 
 function SpawnEnemies (wave : int)
 {
     var spawnNum = (defaultSpawnNumber + 3 * (wave - 1));
     
     isSpawning = true;
     
     for(var i = 0; i < spawnNum;i++)
     {
         yield WaitForSeconds(Random.Range (yieldTimeMin, yieldTimeMax));
         
         var object : GameObject = enemyPrefabs [Random.Range (0, enemyPrefabs.Length)];
         var Position : Transform = spawnPionts [Random.Range (0, spawnPionts.length)];
         
         Instantiate (object, Position.position +
             Vector3 (Random.Range (spawnXOffsetMin, spawnXOffsetMax), 0,
             Random.Range (spawnZOffsetMin, spawnZOffsetMax)), Position.rotation);
                 
         enemyCounter++;                        
     }
     
     isSpawing = false;
 {      
     
 function UpdateWave();
 
 {
     waveNumber++;
     SpawnEnemies(waveNumber);
 }           
 
 function Start () 
 {
     SpawnEnemies(waveNumber);
 }
 
 function Update () 
 {
     if(enemyCounter == 0 && !isSpawing)
     {
         UpdateWave();
     }
 }