Enemy Wave System Error

Hi, i have this script that creates different types of waves however once all the enemies have been killed another wave doesn's spawn. can someone look at my script and see if there is something wrong with it. Looking through the script there is code to spawn more enemies when there is <0 but it isnt working for some reason. This is the script:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;

 public class Spawner : MonoBehaviour
 {
 // Color of the gizmo
 public Color gizmoColor = Color.red;
 
 //-----------------------------------
 // All the Enums
 //-----------------------------------
 // Spawn types
 public enum SpawnTypes
 {
     Normal,
     Once,
     Wave,
     TimedWave
 }
 // The different Enemy levels
 public enum EnemyLevels
 {
     Easy,
     Medium,
     Hard,
     Boss
 }
 //---------------------------------
 // End of the Enums
 //---------------------------------
 
 // Enemy level to be spawnedEnemy
 public EnemyLevels enemyLevel = EnemyLevels.Easy;
 
 //----------------------------------
 // Enemy Prefabs
 //----------------------------------
 public GameObject EasyEnemy;
 public GameObject MediumEnemy;
 public GameObject HardEnemy;
 public GameObject BossEnemy;
 private Dictionary<EnemyLevels, GameObject> Enemies = new Dictionary<EnemyLevels, GameObject>(4);
 //----------------------------------
 // End of Enemy Prefabs
 //----------------------------------
 
 //----------------------------------
 // Enemies and how many have been created and how many are to be created
 //----------------------------------
 public int totalEnemy = 10;
 private int numEnemy = 0;
 private int spawnedEnemy = 0;
 //----------------------------------
 // End of Enemy Settings
 //----------------------------------
 
 
 // The ID of the spawner
 private int SpawnID;
 
 //----------------------------------
 // Different Spawn states and ways of doing them
 //----------------------------------
 private bool waveSpawn = false;
 public bool Spawn = true;
 public SpawnTypes spawnType = SpawnTypes.Normal;
 // timed wave controls
 public float waveTimer = 30.0f;
 private float timeTillWave = 10.0f;
 //Wave controls
 public int totalWaves = 5;
 private int numWaves = 0;
 //----------------------------------
 // End of Different Spawn states and ways of doing them
 //----------------------------------
 void Start()
 {
     // sets a random number for the id of the spawner
     SpawnID = Random.Range(1, 500);
     Enemies.Add(EnemyLevels.Easy, EasyEnemy);
     Enemies.Add(EnemyLevels.Boss, BossEnemy);
     Enemies.Add(EnemyLevels.Medium, MediumEnemy);
     Enemies.Add(EnemyLevels.Hard, HardEnemy);
 }
 // Draws a cube to show where the spawn point is... Useful if you don't have a object that show the spawn point
 void OnDrawGizmos()
 {
     // Sets the color to red
     Gizmos.color = gizmoColor;
     //draws a small cube at the location of the gam object that the script is attached to
     Gizmos.DrawCube(transform.position, new Vector3 (0.5f,0.5f,0.5f));
 }
 void Update ()
 {
     if(Spawn)
     {
         // Spawns enemies everytime one dies
         if (spawnType == SpawnTypes.Normal)
         {
             // checks to see if the number of spawned enemies is less than the max num of enemies
             if(numEnemy < totalEnemy)
             {
                 // spawns an enemy
                 spawnEnemy();
             }
         }
         // Spawns enemies only once
         else if (spawnType == SpawnTypes.Once)
         {
             // checks to see if the overall spawned num of enemies is more or equal to the total to be spawned
             if(spawnedEnemy >= totalEnemy)
             {
                 //sets the spawner to false
                 Spawn = false;
             }
             else
             {
                 // spawns an enemy
                 spawnEnemy();
             }
         }
         //spawns enemies in waves, so once all are dead, spawns more
         else if (spawnType == SpawnTypes.Wave)
         {
             if(numWaves < totalWaves + 1)
             {
                 if (waveSpawn)
                 {
                     //spawns an enemy
                     spawnEnemy();
                 }
                 if (numEnemy == 0)
                 {
                     // enables the wave spawner
                     waveSpawn = true;
                     //increase the number of waves
                     numWaves++;
                 }
                 if(numEnemy == totalEnemy)
                 {
                     // disables the wave spawner
                     waveSpawn = false;
                 }
             }
         }
         // Spawns enemies in waves but based on time.
         else if(spawnType == SpawnTypes.TimedWave)
         {
             // checks if the number of waves is bigger than the total waves
             if(numWaves <= totalWaves)
             {
                 // Increases the timer to allow the timed waves to work
                 timeTillWave += Time.deltaTime;
                 if (waveSpawn)
                 {
                     //spawns an enemy
                     spawnEnemy();
                 }
                 // checks if the time is equal to the time required for a new wave
                 if (timeTillWave >= waveTimer)
                 {
                     // enables the wave spawner
                     waveSpawn = true;
                     // sets the time back to zero
                     timeTillWave = 0.0f;
                     // increases the number of waves
                     numWaves++;
                     // A hack to get it to spawn the same number of enemies regardless of how many have been killed
                     numEnemy = 0;
                 }
                 if(numEnemy >= totalEnemy)
                 {
                     // diables the wave spawner
                     waveSpawn = false;
                 }
             }
             else
             {
                 Spawn = false;
             }
         }
     }
 }
 // spawns an enemy based on the enemy level that you selected
 private void spawnEnemy()
 {
     GameObject Enemy = (GameObject) Instantiate(Enemies[enemyLevel], gameObject.transform.position, Quaternion.identity);
     Enemy.SendMessage("SetName", SpawnID);
     // Increase the total number of enemies spawned and the number of spawned enemies
     numEnemy++;
     spawnedEnemy++;
 }
 // Call this function from the enemy when it "dies" to remove an enemy count
 public void killEnemy(int sID)
 {
     // if the enemy's spawnId is equal to this spawnersID then remove an enemy count
     if (SpawnID == sID)
     {
         numEnemy--;
     }
 }
 //enable the spawner based on spawnerID
 public void enableSpawner(int sID)
 {
     if (SpawnID == sID)
     {
         Spawn = true;
     }
 }
 //disable the spawner based on spawnerID
 public void disableSpawner(int sID)
 {
     if(SpawnID == sID)
     {
         Spawn = false;
     }
 }
 // returns the Time Till the Next Wave, for a interface, ect.
 public float TimeTillWave
 {
     get
     {
         return timeTillWave;
     }
 }
 // Enable the spawner, useful for trigger events because you don't know the spawner's ID.
 public void enableTrigger()
 {
     Spawn = true;
 }

}