Trying to change a texture with picture from camera

On android i'm using WebCamTexture to take a photo(GetPixel), so i use this code, i want that the player can change the camo texture of my weapon with his camera, this is just a test, i know how i will make the interface, but the code is not working, i'm using one cube to show my camera, it work, the problem is, after pressing Fire1(LeftCtrl) it supposed to take a photo and replace the texture from the another cube, the first cube is just like a plane on a GUI to show the player what the camera is taking, and the another cube is supposed to be like a gun, before testing in a real gun i want this code to work, but i don't know the problem.

 using UnityEngine;
 using System.Collections;
 
 public class ChangeTextureWCam : MonoBehaviour {
 
     public int cameraWidth = 640;
     public int cameraHeight = 480;
     public Texture2D snap;
     public WebCamTexture wct;
     public GameObject anotherCube;
     void Start() {
         wct = new WebCamTexture(2000, 2000, 30);
         renderer.material.mainTexture = wct;
         wct.Play();
     }
     void Update(){
         if(Input.GetButtonDown("Fire1")){
             snap.SetPixels(wct.GetPixels());
             snap.Apply();
             anotherCube.renderer.material.mainTexture = snap;
         }
     }
 }