Admob Work Only In empty project But Not in My Game...!!

Hello I Have a Strange problem with admob is work in empty project (i attach the The Script with main camera is Work in real device) But if i attach script with main camera of my game... admob not work Plaise help me and sorry for my english (i follow this tuto https://www.youtube.com/watch?v=5OLp5NafqK0)

 using UnityEngine;
 using System.Collections;
 using GoogleMobileAds.Api;
 
 public class LoadAd : MonoBehaviour {
 
     // Use this for initialization
     void Start () 
     {
         RequestBanner();
     }
     
     // Update is called once per frame
     void Update () 
     {
     
     }
 
     private void RequestBanner()
     {
         #if UNITY_ANDROID
         string adUnitId = "ca-app-pub-3940256099942544/6300978111";
         #elif UNITY_IPHONE
         string adUnitId = "INSERT_IOS_BANNER_AD_UNIT_ID_HERE";
         #else
         string adUnitId = "unexpected_platform";
         #endif
         
         // Create a 320x50 banner at the top of the screen.
         BannerView bannerView = new BannerView(adUnitId, AdSize.SmartBanner, AdPosition.Bottom);
         // Create an empty ad request.
         AdRequest request = new AdRequest.Builder().Build();
         // Load the banner with the request.
         bannerView.LoadAd(request);
     }
 }