I'm going nuts for 2 days about NullReferenceException error please help!

Hello guys. My main character will pick an object “Pick ups” and Police will chase him(AIThirdpersonController). I couln’t do it no matter what. Plase take a look at my codes. I’m trying to acces a function from another one. Thank you

Thats my PlayerController script on my main character(Wilson);

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.AI;
using UnityStandardAssets.Characters.ThirdPerson;

public class PlayerController : MonoBehaviour {
    public float speed;
    public Text countText;
    public Text winText;
    AICharacterControl PoliceRun;
    GameObject Winston;
    private GameObject police;

    public  int count;
    private Rigidbody rb;
    Transform target;
    private Vector3 place;
    string count1;

    // Use this for initialization
    void Start() {
        rb = GetComponent<Rigidbody>();
        count = 0;
        winText.text = "";

        police = GameObject.FindWithTag("Police");
        Winston = GameObject.FindWithTag("Winston");
        PoliceRun = GameObject.FindWithTag("Police").GetComponent<AICharacterControl>();


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


    private void FixedUpdate()


    void OnTriggerEnter(Collider other) {
        if (other.gameObject.CompareTag("Pick Up")) ;
            count = count + 1;


    void SetCountText() {
        count1 = countText.text;
        countText.text = "Collected=" + count.ToString();
        if (count >= 12 )
            winText.text = "WIN!";


    void SetTargetAI()


And Thats AICharacterControl (police) ;

using System;
using UnityEngine;
using UnityStandardAssets.Characters.ThirdPerson
namespace UnityStandardAssets.Characters.ThirdPerson
    public class AICharacterControl : MonoBehaviour
        public UnityEngine.AI.NavMeshAgent agent { get; private set; }             // the navmesh agent required for the path finding
        public ThirdPersonCharacter character { get; private set; } // the character we are controlling
        public Transform target;                                    // target to aim for

        PlayerController pc;
        Transform WinstonT;

        private void Start()
            // get the components on the object we need ( should not be null due to require component so no need to check )
            agent = GetComponentInChildren<UnityEngine.AI.NavMeshAgent>();
            character = GetComponent<ThirdPersonCharacter>();

            agent.updateRotation = false;
            agent.updatePosition = true;

            pc = GameObject.FindWithTag("Police").GetComponent<PlayerController>();
            WinstonT = GameObject.FindWithTag("Winston").transform;


        private void Update()
            if (target != null)

            if (agent.remainingDistance > agent.stoppingDistance)
                character.Move(agent.desiredVelocity, false, false);
                character.Move(Vector3.zero, false, false);

        public void SetTarget(Transform target)
            this.target = target;

I’m getting this error.

NullReferenceException: Object reference not set to an instance of an object
PlayerController.SetTargetAI () (at Assets/Scripts/PlayerController.cs:74)
PlayerController.OnTriggerEnter (UnityEngine.Collider other) (at Assets/Scripts/PlayerController.cs:53

The only thing I see is that one the private members were not assigned. Try adding the following checks.

police = GameObject.FindWithTag("Police");
Winston = GameObject.FindWithTag("Winston");
PoliceRun = GameObject.FindWithTag("Police").GetComponent<AICharacterControl>();
if (!police)
    Debug.LogWarning ("police not found");
if (!Winston)
    Debug.LogWarning ("Winston not found");
if (!PoliceRun)
    Debug.LogWarning ("PoliceRun not found");

I’ve tried it, but no warning showed up :confused: