cannot show my hazard in space shooter

hi gays~

I follow the space shooter in unity and have problem now

I finish chapter 11 of space shooter which is explosions and then I cannot show hazard in play mode end of the came controller part

i don't know why......T^T...

gays please help me

I made Asteroid prefab and then deleted of Asteroid game object in hierarchy also my asteroid prefab has 'random rotator' 'mover' 'destroy by contact' scripts and 'rigid body' and 'capsule colander'.

I exactly wrote c# script from tutorial and did not copy 'done' scripts

My game controller object has game controller script and include asteroid prefab ..........

i really do not have any idea, why i cannot show may Asteroid in play move

My space shooter does not have any error and warning

help me..... pleaze

This is my came controller script

using UnityEngine; using System.Collections;

public class GameConroller : MonoBehaviour {

 public GameObject hazard;
 public Vector3 spawnValues;

 void start(){
     SpawnWaves ();
 }

 void SpawnWaves()
 {
     Vector3 spawnPosition = new Vector3 (Random.Range(-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
 
     Quaternion spawnRotation = Quaternion.identity;

     Instantiate (hazard, spawnPosition, spawnRotation);        
     
 }

}