I have a error in my Script

Unity Engine
1

What is the Problem???
My Error Code is

using UnityEngine;
using System.Collections;

public class HealthController : MonoBehaviour {
    public float startHealth = 5;
    public int startLifePoints = 3;
    private float health = 5;
    private int lifePoints = 3;

    private Animator anim;
    private PlayerController playerController;
    private bool isDead = false;
    private bool isDamageable = true;

    // Use this for initialization
    void Start () {
        anim = GetComponent<Animator> ();
        playerController = GetComponent<PlayerController> ();

        if (Application.loadedLevel == 0) {
            health = startHealth;
            lifePoints = startLifePoints;
        } else {
            health = PlayerPrefs.GetFloat ("Health");
            lifePoints = PlayerPrefs.GetInt ("LifePoints");
        }
    }

    void ApplyDamage(float damage) {
        health -= damage;

        health = Mathf.May (0, health);

        if (!isDead) {

            if (health == 0) {
                isDead = true;
                Dying ();
            } else {
                if (isDamageable) {
                    Damaging ();           
                }
            }

            isDamageable = false;
            Invoke ("ResetIsDamagable", 1);
        }
    }

    void ResetIsDamagable() {
        isDamageable = true;
    }

    void Dying() {
        anim.SetBool ("Dying", true);

        playerController.enabled = false;
        lifePoints --;

        if (lifePoints <= 0) {
            //startgame
            Invoke ("StartGame" , 3);
        } else {
            //Restart Level
            Invoke ("RestartLevel", 1);
        }
    }

    void StartGame() {
        Application.LoadLevel (0);
    }

    void RestartLevel() {
        health = startHealth;
        isDead = false;
        anim.SetBool ("Dying", false);
        playerController.enabled = true;

        if (!playerController.lookingRight) {
            playerController.Flip();
        }
    }

    void Damaging() {
        anim.SetTrigger ("Damage");
    }

    void OnDestroy() {
        PlayerPrefs.SetFloat ("Health", health);
        PlayerPrefs.Setint ("LifePoints", lifePoints);
    }
}
2

you don’t have a script called “PlayerController” in you project… did you import the standard assets pack when you created the project?