Enemy spawn script not working properly !

 var enemy : GameObject;
 var timeDelay = 3;
 var ready = true;
 var timer : int = 240;
 var limit : int = 40;
 var left : int = 40;
 var grip : Transform;
  
 function Start(){
 ready = true;
 if(ready){
     if(timer > 0){
     timer -= 1;
     while (ready) {
         yield WaitForSeconds(timeDelay);
         Instantiate( enemy, transform.position, Quaternion.identity);
         enemy.transform.LookAt(grip);
         limit -=1;
         enemy.transform.Translate(Vector3(0,0,1));
     }
     }
     }
     
     if(timer <=0){
     Time.timeScale = 1;
     guiText.text == "GAME OVER , HAHAHAHA !!!";
     yield WaitForSeconds(3);
     Application.LoadLevel("levelSelect");
     }
     //ENEMIES IN THIS LEVEL = 80;
 if(left == 0){
     guiText.text == "WELL DONE GREENHORN , YOU FINISHED LEVEL 1 ! BUT , ARE YOU READY FOR THE NEXT LEVEL !";
     yield WaitForSeconds(3);
     Application.LoadLevel("level2");
     }
     
     if(enemy == null){
     left-=1;
     }
     if(limit == 0){
     ready = false;
     }
     
 }

At the moment it just spawns enemies and they fly into the air ??? Help !