Adding instances of objects into generic list

Hello guys, I am working on simple tower defense game and I have a problem with adding GameObjects I instantiated to list. Simply, when I add instance to a list, another instance will not be instantiated…

This code is for spawning enemies and adding them to list.

using UnityEngine;
using System.Collections;

public class GameController : MonoBehaviour {

    public Transform spawnPoint;
    public GameObject enemy;
    public GameObject tower;
    private Ray ray;
    private RaycastHit hit;

	// Use this for initialization
	void Start () {

	// Update is called once per frame
	void Update () {

        if(Input.GetButtonDown("Fire1")) {
            ray = Camera.main.ScreenPointToRay(Input.mousePosition);

            if(Physics.Raycast(ray.origin, ray.direction * 100f, out hit)) {
                Instantiate(tower, hit.point + Vector3.up * 0.5f, Quaternion.identity);

    IEnumerator SpawnMinions() {
        while(true) {
            for(int i = 0; i < 5; i++) {
                GameObject enemyInstance = Instantiate(enemy, spawnPoint.position, transform.rotation) as GameObject;
                yield return new WaitForSeconds(0.5f);
                Tower.enemies.Add(enemyInstance); // when I remove this line of code, it instantiates 5 enemies. But with it, it instantiates only 1... It behaves like return command in function.
            yield return new WaitForSeconds(3f);

And then here is Tower script… Code should check, if there is at least 1 enemy in list and if it is and is in specific range from tower, then start shoot enemy until it is destroyed:

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

public class Tower : MonoBehaviour {

	public GameObject bullet;
    public static List<GameObject> enemies;
    public int time;

    void Start() {


    void Update() {

        time = (int)(Time.time);

        if(enemies.Count > 0) {
            for(int i = 0; i < enemies.Count; i++) {
                while(enemies*.gameObject != null) { // while current object exists*

if(time % 2 == 0 && (Vector3.Distance(transform.position, enemies*.transform.position) < 2)) {*

Instantiate(bullet, transform.position, transform.rotation);
bullet.SendMessage(“Fire”, enemies*.transform.position - transform.position);*

if(Vector3.Distance(transform.position, enemies*.transform.position) > 2) break;*
And really simple bullet script:
using UnityEngine;
using System.Collections;

public class Bullet : MonoBehaviour {

* // Use this for initialization*
* void Start () {*

* }*

* // Update is called once per frame*
* public void Fire (Transform target) {*

_ rigidbody.AddForce(target.position * 1.5f * Time.deltaTime);
* }
Unity writes this error, when I start the game… Really don’t know what does it mean:
NullReferenceException: Object reference not set to an instance of an object
GameController+c__Iterator0.MoveNext () (at Assets/Scripts/GameController.cs:39)
And when I instantiate tower, it keeps writing:
NullReferenceException: Object reference not set to an instance of an object
Tower.Update () (at Assets/Scripts/Tower.cs:19)
(Saying, that error is on this line of code: if(enemies.Count > 0))*_

Enemies is null, you need to initialize it. So yeah, with generic or anything at all you should initialise them for them to work. For example your boss says put this box in section null, section null doesn’t exist so you can’t place it there. Same things with list.

List<GameObject> enemies = new List<GameObject>();