Enemy damage script is not working

Hello, I've been trying to figure out this issue for many hours but I'm having no luck. I'm using projectile bullets and I basically want my enemy object to take an X amount of damage before the object is destroyed. I'm not really sure where the problem lies within the script. Any help would be greatly appreciated!

This is my Gun script

 using UnityEngine;
 using TMPro;
 public class Gunbullets : MonoBehaviour
 {
 
     //bullet
     public GameObject bullet;
     public float damage = 10f;
    // public GameObject impactEffect;
 
 
     //bullet force 
 
     public float shootForce, upwardForce;
 
     //Gun stats
     public float timeBetweenShooting, spread, reloadTime, timeBetweenShots;
     public int MagazineSize, bulletsPerTap;
     public bool allowButtonHold;
 
     int bulletsLeft, bulletshot;
 
     //Recoil 
     public Rigidbody playerRb;
     public float recoilForce;
 
 
     //bools
     bool shooting, readyToShoot, reloading;
 
     //Reference
     public Camera Camera;
     public Transform attackPoint;
 
     //Graphics
     public GameObject muzzleFlash;
     public TextMeshProUGUI ammunitionDisplay;
 
     public bool allowInvoke = true;
 
     private void Awake()
     {
 
         //make sure magazine is full
         bulletsLeft = MagazineSize;
         readyToShoot = true;
     }
 
     private void Update()
     {
         MyInput();
 
         //Set Ammo Display
         if (ammunitionDisplay != null)
             ammunitionDisplay.SetText(bulletsLeft / bulletsPerTap + " / " + MagazineSize / bulletsPerTap);
     }
     private void MyInput()
     {
         //Check if allowed to hold down button and take correspinginput 
         if (allowButtonHold) shooting = Input.GetKey(KeyCode.Mouse0);
         else shooting = Input.GetKey(KeyCode.Mouse0);
 
         //Reloading
         if (Input.GetKeyDown(KeyCode.R) && bulletsLeft < MagazineSize && !reloading) Reload();
         //Reload automatically when trying to shoot without ammo
         if (readyToShoot && shooting && !reloading && bulletsLeft <= 0) Reload();
 
         //Shooting
         if (readyToShoot && shooting &&!reloading && bulletsLeft > 0 )
         {
             //set bullets shot to 0 
             bulletshot = 0;
 
            Shoot();
 
         }
     }
 
     private void Shoot()
     {
 
         readyToShoot = false;
 
         Ray ray = Camera.ViewportPointToRay(new Vector3(0.5f, 0.5f, 0));
         RaycastHit hit;
         //check if ray hits something 
         Vector3 targetPoint;
         if (Physics.Raycast(ray, out hit))
             targetPoint = hit.point;
 
         else
             targetPoint = ray.GetPoint(75);
 
         //calculate direction from attackPoint to targetPoint 
 
         Vector3 directionWithoutSpread = targetPoint - attackPoint.position;
 
         //calculate spread 
 
         float x = Random.Range(-spread, spread);
         float y = Random.Range(-spread, spread);
 
         //calculate new direction with spread 
         Vector3 directionWithSpread = directionWithoutSpread + new Vector3(x, y, 0);
 
         //instantiate bullet/projectile 
 
         GameObject currentBullet = Instantiate(bullet, attackPoint.position, Quaternion.identity);
 
         //Roate bullet to shoot direction 
         currentBullet.transform.forward = directionWithSpread.normalized;
 
         //Add force to bullet 
         currentBullet.GetComponent<Rigidbody>().AddForce(directionWithSpread.normalized * shootForce, ForceMode.Impulse);
         currentBullet.GetComponent<Rigidbody>().AddForce(Camera.transform.up * upwardForce, ForceMode.Impulse);
 
       
         //Instantiate muzzle flash, if you have one 
 
         if (muzzleFlash != null)
             Instantiate(muzzleFlash, attackPoint.position, Quaternion.identity);
 
         bulletsLeft--;
         bulletshot++;
 
         //invoke reset shot function (if not already invoked) 
         if (allowInvoke)
         {
             Invoke("ResetShot", timeBetweenShooting);
             allowInvoke = false;
 
             //Add recoil to player 
             playerRb.AddForce(-directionWithSpread.normalized * recoilForce, ForceMode.Impulse);
 
         }
 
         // if more than one  bullets per Tap make sure to repeat shoot function 
         if (bulletshot < bulletsPerTap && bulletsLeft > 0)
 
             Invoke("Shoot", timeBetweenShots);
 
         Target target = hit.transform.GetComponent<Target>();
         if (target != null)
         {
             target.TakeDamage(damage);
         }
 
     }
 
     private void ResetShot()
     {
         readyToShoot = true;
         allowInvoke = true;
     }
 
     private void Reload ()
     {
         reloading = true;
         Invoke("ReloadFinished", reloadTime);
     }
     private void ReloadFinished()
 
     {
         bulletsLeft = MagazineSize;
         reloading = false;
     }
 }
 

And this is my Enemy Script

using UnityEngine; using UnityEngine.AI;

public class AiTutorial : MonoBehaviour { public NavMeshAgent agent;

 public Transform player;

 public LayerMask whatIsGround, whatIsPlayer;

 public float health;

 public float damage;
 //Patroling
 public Vector3 walkPoint;
 bool walkPointSet;
 public float walkPointRange;

 //Attacking
 public float timeBetweenAttacks;
 bool alreadyAttacked;
 public GameObject projectile;

 //States
 public float sightRange, attackRange;
 public bool playerInSightRange, playerInAttackRange;

 public int life = 50;

 public void OnCollisionEnter(Collision boom)
 {
     if (boom.transform.tag == "bullet")
     { 

      health -= damage;

     Destroy(boom.gameObject);
 }


     // the object that triggered this collision is tagged "bullet"
     //if (boom.gameObject.tag == "bullet")
     //    {
     //      life += 1;
     //       if (life == 50)
     //           Destroy(gameObject);
     //  }
     }

 private void Awake()
 {
     player = GameObject.Find("Cylinderfps").transform;
     agent = GetComponent<NavMeshAgent>();
 }

 private void Update()
 {
     //Check for sight and attack range
     playerInSightRange = Physics.CheckSphere(transform.position, sightRange, whatIsPlayer);
     playerInAttackRange = Physics.CheckSphere(transform.position, attackRange, whatIsPlayer);

     if (!playerInSightRange && !playerInAttackRange) Patroling();
     if (playerInSightRange && !playerInAttackRange) ChasePlayer();
     if (playerInAttackRange && playerInSightRange) AttackPlayer();
 }

 private void Patroling()
 {
     if (!walkPointSet) SearchWalkPoint();

     if (walkPointSet)
         agent.SetDestination(walkPoint);

     Vector3 distanceToWalkPoint = transform.position - walkPoint;

     //Walkpoint reached
     if (distanceToWalkPoint.magnitude < 1f)
         walkPointSet = false;
 }
 private void SearchWalkPoint()
 {
     //Calculate random point in range
     float randomZ = Random.Range(-walkPointRange, walkPointRange);
     float randomX = Random.Range(-walkPointRange, walkPointRange);

     walkPoint = new Vector3(transform.position.x + randomX, transform.position.y, transform.position.z + randomZ);

     if (Physics.Raycast(walkPoint, -transform.up, 2f, whatIsGround))
         walkPointSet = true;
 }

 private void ChasePlayer()
 {
     agent.SetDestination(player.position);
 }

 private void AttackPlayer()
 {
     //Make sure enemy doesn't move
     agent.SetDestination(transform.position);

     transform.LookAt(player);

     if (!alreadyAttacked)
     {
         ///Attack code here
         Rigidbody rb = Instantiate(projectile, transform.position, Quaternion.identity).GetComponent<Rigidbody>();
         rb.AddForce(transform.forward * 32f, ForceMode.Impulse);
         rb.AddForce(transform.up * 8f, ForceMode.Impulse);
         ///End of attack code

         alreadyAttacked = true;
         Invoke(nameof(ResetAttack), timeBetweenAttacks);
     }
 }
 private void ResetAttack()
 {
     alreadyAttacked = false;
 }

 public void TakeDamage(int damage)
 {
     health -= damage;

     if (health <= 0) Invoke(nameof(DestroyEnemy), 0.5f);
 }
 private void DestroyEnemy()
 {
     Destroy(gameObject);
 }

 private void OnDrawGizmosSelected()
 {
     Gizmos.color = Color.red;
     Gizmos.DrawWireSphere(transform.position, attackRange);
     Gizmos.color = Color.yellow;
     Gizmos.DrawWireSphere(transform.position, sightRange);
 }

}