[SOLVED]The script don't execute after scene reloading

I have this script which don't execute after reloading scene from a button but execute when doing the same thing from another button with the same line of code:

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;   
 public class WaveSpawner : MonoBehaviour {
 
     public static int EnemiesAlive = 0;
 
     public Wave[] waves;
     
     public Transform[] spawnPoints;
 
     public float timeBetweenWaves = 5f;
     public float countdown = 2f;
 
     //public float timeBetweenEnemies = 0.5f;
 
     public Text waveCountdownText;
     public Text wavesText;
 
     private int waveIndex = 0;
 
     private void Awake()
     {
         this.enabled = true;
     }
 
     private void Start()
     {
         Debug.Log(waveIndex + " " + waves.Length + " " + this.enabled);
 
         if (spawnPoints.Length == 0)
         {
             Debug.LogError("No spawn points referenced!");
         }
     }
 
     private void Update()
     {
         if(EnemiesAlive > 0)
         {
             return;
         }
 
         if (waveIndex == waves.Length)
         {
             Debug.Log("LEVEL WON!");
             this.enabled = false;
         }
 
         if (countdown <= 0f)
         {
             if(waveIndex == waves.Length)
             {
                 return;
             }
             StartCoroutine(SpawnWave());
             countdown = timeBetweenWaves;
             return;
         }
 
         countdown -= Time.deltaTime;
 
         countdown = Mathf.Clamp(countdown, 0f, Mathf.Infinity);
 
         waveCountdownText.text = string.Format("{0:00.00}", countdown);
 
         wavesText.text = (waveIndex + 1) + "/" + waves.Length;
     }
 
     //IEnumerator SpawnWave()
     //{
     //    //Debug.Log("Wave Incoming");
 
     //    Wave wave = waves[waveIndex];
 
     //    for (int i = 0; i < wave.count; i++)
     //    {
     //        SpawnEnemy(wave.enemy);
     //        yield return new WaitForSeconds(1f / wave.rate);
     //    }
 
     //    waveIndex++;
     //    PlayerStats.Rounds++;
 
     //    if(waveIndex == waves.Length)
     //    {
     //        Debug.Log("LEVEL WON!");
     //        this.enabled = false;
     //    }
     //}
 
     IEnumerator SpawnWave()
     {
         //Debug.Log("Wave Incoming");
         
         Wave wave = waves[waveIndex];
 
         for (int a = 0; a < wave.waveCount; ++a)
         {
             Transform sp = spawnPoints[Random.Range(0, spawnPoints.Length)];
             yield return new WaitForSeconds(1f / wave.waveRate);
 
             for (int i = 0; i < wave.enemyWave.Length; i++)
             {
                 for (int j = 0; j < wave.enemyWave[i].enemyCount; ++j)
                 {
                     SpawnEnemy(wave.enemyWave[i].enemy, sp);
                     yield return new WaitForSeconds(1f / wave.enemyWave[i].enemyRate);
                 }
             }
         }
 
         waveIndex++;
         PlayerStats.Rounds++;
 
         //if (waveIndex == waves.Length)
         //{
         //    Debug.Log("LEVEL WON!");
         //    this.enabled = false;
         //}
     }
 
     void SpawnEnemy(GameObject enemy, Transform _sp)
     {
         Instantiate(enemy, _sp.position, _sp.rotation);
         EnemiesAlive++;
     }
 
     //void DestroyEnemyOnTargetReach()
     //{
     //    Destroy(gameObject);
     //}
 }