NullReferenceException when trying to drag object

Hi,

I'm trying to drag the spawned object only on the y-axis.
The code works on a scene without using ARCore, but when using it in a scene with ARCore I get an NullReferenceException error. Isn't it possible to drag objects in AR?

This is the code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Drag : MonoBehaviour
6. {
7.     private Vector3 screenPoint;
8.     private Vector3 offset;
9.  
10.     void OnMouseDown()
11.     {
12.         screenPoint = Camera.main.WorldToScreenPoint(gameObject.transform.position);
13.         offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));
14.     }
15.  
16.     void OnMouseDrag()
17.     {
18.         Vector3 cursorPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);
19.         Vector3 cursorPosition = Camera.main.ScreenToWorldPoint(cursorPoint) + offset;
20.         transform.position = new Vector3(transform.position.x, cursorPosition.y, transform.position.z);
21.     }
22.  
23. }
24.  

 

I fixed it, it didn't find the camera. So I made a camera variable and put the ar camera in it.