when i press the start (menu) button then Console says error. Error: NullReferenceException: Object reference not set to an instance of an object uiManager.Update () (at Assets/scripts/uiManager.cs:21) pls help me!

Questions & Answers
1

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

public class uiManager : MonoBehaviour {

public Text ScoreText;
bool gameOver;
int score;

// Use this for initialization
void Start() {
    gameOver = false;
    score = 0;
    InvokeRepeating ("scoreUpdate", 1.0f, 0.5f);

}

// Update is called once per frame
void Update() {
    ScoreText.text = "Score: " + score;
}

void scoreUpdate(){
    if(gameOver == false) {
        score += 1; 
    }
}
public void gameOverActivated(){
    gameOver = true;

}

public void Play(){
    Application.LoadLevel ("level1");
}

public void Pause()
{
    if (Time.timeScale == 1)
    {
        Time.timeScale = 0;
    }
    else if (Time.timeScale == 0)
    {
        Time.timeScale = 1;

    }
}

public void Replay(){
    Application.LoadLevel (Application.loadedLevel);

}

public void Menu (){

    Application.LoadLevel ("menu");

}
public void Exit(){
    Application.Quit ();
}

}

2

The first thing to check would be if the ScoreText variable has been assigned in the Inspector. It is declared as public here, so can be assigned within the Inspector for this script component.