Spaceshooter enemy spawning problem

Hi Unity answers. I am trying to make a space shooter but i cant get the enmy to spawn. i have checked my script through so many times but i can not find the problem. here is my script.

using UnityEngine; using System.Collections;

public class GameController : 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);
 }

}