Wave Spawner not working ｜Does not detect if an object is destroyed

Hey, I have a question regarding this script. I have watched this tutorial several times but I can't detect the error. Can someone help me? The script is spawning 2 Enemies like i said it should do, but its not detecting if delete these Enemies. I appreciate any answer. Thanks in advance! Finn Part 1 https://www.youtube.com/watch?v=Vrld13ypX_I Part 2 https://www.youtube.com/watch?v=q0SBfDFn2Bs using System.Collections; using System.Collections.Generic; using UnityEngine; public class WaveSpawner : MonoBehaviour { public enum SpawnState { Spawning, Waiting, Counting } // state of the Wave [System.Serializable] public class Wave { public string name; //wave name: Easy public Transform enemy; //Which Prefab should be spawned: Enemy public int count; //how much Enemys should be spawned per wave: 6 public float rate; //how often the count of enemies should spawn } public Wave[] waves; private int nextWave = 0; public float timeBetweenWaves = 5f; //Time between waves: 5f = 5seconds public float waveCountdown; //time Counting down to next wave: 3... 2... 1... private float searchCountdown = 1f; // how long to search for alive enemies private SpawnState state = SpawnState.Counting; void Start() { waveCountdown = timeBetweenWaves; } void Update() { if (state == SpawnState.Waiting) //starts method to check if enemies are still alive { searchCountdown = 1f; //search countdown 1s if (!EnemyIsAlive()) { //begin a new Wave Debug.Log("Wave Completed!"); return; } else { return; } } if (waveCountdown <= 0) //ask if ready for new Wave { if (state != SpawnState.Spawning) //ask if Waves are already spawning { StartCoroutine( SpawnWave ( waves[nextWave] ) ); //start Spawning Routine } } else { waveCountdown -= Time.deltaTime; //if not count down } } bool EnemyIsAlive() //method to search for living enemies { searchCountdown -= Time.deltaTime; //count down search time if (searchCountdown <= 0f) //if search countdown = 0 { if (GameObject.FindGameObjectWithTag("Enemy") == null) //check if enemy is alive { return false; //enemies arent allive } } return true; // enemies are allive } IEnumerator SpawnWave (Wave _wave) //Spawning Routine { Debug.Log("Spawning Wave: " + _wave.name); state = SpawnState.Spawning; //State: Spawning for (int i = 0; i < _wave.count; i++) //loop through amount of enemy { SpawnEnemy(_wave.enemy); //spawn enemy Method yield return new WaitForSeconds(1f / _wave.rate); //time between spawning of each enemy } state = SpawnState.Waiting; //State: Waiting yield break; //stop } void SpawnEnemy (Transform _enemy) //spawn enemy Method { Debug.Log("Spawning Enemy: " + _enemy.name); Instantiate(_enemy, transform.position, transform.rotation); } }