Enemy Damage Script Problem!

using UnityEngine;
using System.Collections;

public class EnemyAttack : MonoBehaviour {

	public float maxDistance;
	public float coolDownTimer;
	public PlayerHealth ph;
	public int damage;

	private Transform myTransform;
	public Transform target;

	// Use this for initialization
	void Start () {
		GameObject go = GameObject.FindGameObjectWithTag ("Player");
		target = go.transform;
		myTransform = transform;
		maxDistance = 3;
		coolDownTimer = 0;
		damage = -10;

		ph = (PlayerHealth) go.GetComponent (typeof(PlayerHealth));
	}
	
	// Update is called once per frame
	void Update () {
		float distance = Vector3.Distance(target.position, myTransform.position);
		if(distance < maxDistance) {
			Attack();
		}

		if(coolDownTimer > 0) {

			coolDownTimer = coolDownTimer - Time.deltaTime;
		}

		if (coolDownTimer < 0) {
			coolDownTimer = 0;
		}
	}

	void Attack() {
		Vector3 dir = Vector3.Normalize(target.position - myTransform.position);
		float direction = Vector3.Dot (dir, transform.forward);
		if (direction > 0) {
     		if(coolDownTimer == 0) {
					coolDownTimer = 2;
	}
  }
}
}

using UnityEngine;
using System.Collections;

public class PlayerHealth : MonoBehaviour {

	public int maxHealth = 100;
	public int curHealth = 0;

	public float healthBarLength;

	// Use this for initialization
	void Start () {
		healthBarLength = Screen.width / 2;
	}

	// Update is called once per frame
	void Update () {
		AddjustCurrentHealth(0);
	}

	void OnGUI() {
		GUI.Box(new Rect(10, 10, healthBarLength, 20), curHealth + "/" + maxHealth);
	}

	public void AddjustCurrentHealth(int adj) {
		curHealth += adj;

		if(curHealth < 0)
			curHealth = 0;

		if(curHealth > maxHealth)
			curHealth = maxHealth;

		if(maxHealth < 1)
			maxHealth = 1;

		healthBarLength = (Screen.width / 2) * (curHealth / (float)maxHealth);
	}
}

using UnityEngine;
using System.Collections;

public class EnemyMovement : MonoBehaviour {

	public int rotateSpeed = 5;
	public int movementspeed = 5;

	public int maxDistance=2;

	private Transform myTransform;
	public Transform target;
	// Use this for initialization
	void Start () {
		GameObject go = GameObject.FindGameObjectWithTag ("Player");
		target = go.transform;

		myTransform = transform;

	}
	
	// Update is called once per frame
	void Update () {
		moveTowardsPlayer ();
	}

	void moveTowardsPlayer () {
		Debug.DrawLine (myTransform.position, target.position, Color.red);
		//rotate enemy
		myTransform.rotation = Quaternion.Slerp(myTransform.rotation, Quaternion.LookRotation(target.position-myTransform.position), rotateSpeed * Time.deltaTime);
		if(Vector3.Distance(target.position, myTransform.position)>maxDistance) {
		//move
			myTransform.position += myTransform.forward * Time.deltaTime;
	}
}
}

using UnityEngine;
using System.Collections;

public class EnemyHealth : MonoBehaviour {

	public int currentHealth;
	public int maximumHealth = 100;

	public float hbLength;

	// Use this for initialization
	void Start () {
		currentHealth = maximumHealth;

		hbLength = Screen.width / 2;
	}

	// Update is called once per frame
	void Update () {
		ChangeHealth (0);

	}

	void OnGUI () {
		GUI.Box (new Rect(10, 50, hbLength, 25), currentHealth +" / " + maximumHealth);
	}

	public void ChangeHealth (int health) {
		hbLength = (Screen.width / 2) * (currentHealth / (float)maximumHealth);
		if(currentHealth <= 0){

			Dead();
		}
	}

	void Dead(){
		Destroy (this.gameObject);
	}
}

I wrote all codes. Thank you for all your answers.

someone help please