I am facing this problem how can i solve it?

NullReferenceException: Object reference not set to an instance of an object
GemSilver.OnTriggerEnter (UnityEngine.Collider other) (at Assets/Scripts/GemSilver.cs:13) //This is the error

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.UI;
5.  
6. public class GemSilver : MonoBehaviour
7. {
8.     public GameObject ScoreBox; // Assign the scoreBox GameObject in the Inspector.
9.     public AudioSource collectSound;
10.  
11.     private void OnTriggerEnter(Collider other)
12.     {
13.         ScoreBox.GetComponent<Text>().text="1000";
14.         collectSound.Play();
15.         Destroy(gameObject);
16.     }
17. }

 

1. Class GemSilver;
2. Line 13;
3. You want to call ScoreBox and an error shows up;
4. You didn't drag and drop ScoreBox in Inspector to the GemSilver component;

Such an error shows up always when you want to call something, if something doesn't exist it's null.

 

I already put it but still cannot work how to solve this problem because the yt video i study is long time ago that was not same version when i do this project