Enemy Clones are broken!

Unity Engine
1

I successfully set up a script that duplicates my enemy from a prefab that I created. The original enemy can approach me and deal damage, but the rest of the enemies cannot! I don’t know why they can’t deal any damage and I would like to fix it.

Here is the script that spawns them:

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

public class SpawnEnemy : MonoBehaviour
{
    public GameObject enemytospawn;
    public Transform spawnplace;
    public int timebetweenspawn;
    public int enemiesperround;

    IEnumerator task()
    {
        for (int i = 0; i < enemiesperround; i++)
        {
            Instantiate(enemytospawn, spawnplace.position, spawnplace.rotation);
            yield return new WaitForSeconds(timebetweenspawn);
        }

    }

    void Awake ()
    {
        StartCoroutine(task());
    }
}

And here is the enemy script itself:

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class EnemyAI : MonoBehaviour
{
    public Transform target;
    public float moveSpeed;
    public int rotationSpeed;
    public float maxdistance = 0.3f;
    private int attackcooldown;
    public Slider HealthSlider;
    public int enemydamage = 3;
    public int enemyhealth;
    public UnityStandardAssets.Characters.FirstPerson.FirstPersonController Controller;

    private Transform myTransform;

    //If the enemy dies...
    void enemydeath ()
    {
        Destroy(gameObject);
    }


    void Awake()
    {
        myTransform = transform;
        attackcooldown = 0;
    }


    void Start()
    {
        GameObject go = GameObject.FindGameObjectWithTag("Player");

        target = go.transform;

        maxdistance = 1.3f;
    }


    IEnumerator Wait()
    {
        yield return new WaitForSeconds(0.4f);
        attackcooldown = 0;
       
    }


    void Update()
    {
        Debug.DrawLine(target.position, myTransform.position, Color.red);


        myTransform.rotation = Quaternion.Slerp(myTransform.rotation, Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed * Time.deltaTime);

        if (Vector3.Distance(target.position, myTransform.position) > maxdistance)
        {
            //Move towards target
            myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
        }
        if (Vector3.Distance(target.position, myTransform.position) < maxdistance && attackcooldown == 0)
        {
            attackcooldown = 1;
            Debug.Log("enemy hit you!");
            Controller.GetComponent<PlayerVitals>().healthSlider.value = Controller.GetComponent<PlayerVitals>().healthSlider.value - enemydamage;
            StartCoroutine (Wait());
        }
        if (enemyhealth <= 0)
        {
            enemydeath();
        }
    }
}

It is also worth mentioning that I cannot get line 67 of the above code to work. No matter what I try it just says
NullReferenceException: object reference not set to an instance of an object

Please help

2

Also I noticed that if I look at the values for the clones of the enemy, the “controller” value is blank. My original enemy has my FPS controller in that slot, but the clones spawn without it.