问为什么我不能展示Interstitial广告？

EN

 using UnityEngine;
 using UnityEngine.UI;
 using System.Text;
 using System.Xml;
 using System.Collections;
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Xml.Serialization;
 using System.IO;
 using GoogleMobileAds;
 using GoogleMobileAds.Api;

 public class responder : MonoBehaviour
 {
     private InterstitialAd interstitial;

     private int gecis;

     public Text questionsorular;
     public Text responseA;
     public Text responseB;
     public Text responseC;
     public Text responseD;
     public Text infoResponses;
     public Text infoResponses1;
     public Text example;
     public Text dogrusayisi;

     private float corrects;
     private float questoesquestions;
     private float media;
     private int Notice;
 }

 void Start()
 {
     RequestInterstitial();
 }

 public void response(string alternative)
 {

     RequestInterstitial();

     if (alternative == "A")
     {
         if (responseA.text == infoResponses.text)
         {
             corrects += 1;
             nextQuestion();
         }
         else
         {
             Invoke("wrong", 1);
         }
     }

     else if (alternative == "B")
     {
         if (responseB.text == infoResponses.text)
         {
             corrects += 1;
             nextQuestion();
         }
         else
         {
             Invoke("wrong", 1);
         }
     }

     else if (alternative == "C")
     {
         if (responseC.text == infoResponses.text)
         {
             corrects += 1;
             nextQuestion();
         }
         else
         {
             Invoke("wrong", 1);
         }
     }

     else if (alternative == "D")
     {
         if (responseD.text == infoResponses.text)
         {
             corrects += 1;
             nextQuestion();
         }
         else
         {
             Invoke("wrong", 1);
         }
     }
 }

 void wrong()
 {
     ShowInterstitial();
     Application.LoadLevel("Notice");
 }

 private void RequestInterstitial()
 {
 #if UNITY_EDITOR
     string adUnitId = "unused";
 #elif UNITY_ANDROID
             string adUnitId = "MY ADS ID";
 #elif UNITY_IPHONE
             string adUnitId = "INSERT_IOS_INTERSTITIAL_AD_UNIT_ID_HERE";
 #else
             string adUnitId = "unexpected_platform";
 #endif

     // Create an interstitial.
     interstitial = new InterstitialAd(adUnitId);
     // Load an interstitial ad.
     interstitial.LoadAd(createAdRequest());
 }

 private AdRequest createAdRequest()
 {
     return new AdRequest.Builder()
             .AddTestDevice(AdRequest.TestDeviceSimulator)
             .AddTestDevice("0123456789ABCDEF0123456789ABCDEF")
             .AddKeyword("game")
             .SetGender(Gender.Male)
             .SetBirthday(new DateTime(1985, 1, 1))
             .TagForChildDirectedTreatment(false)
             .AddExtra("color_bg", "9B30FF")
             .Build();
 }

 private void ShowInterstitial()
 {
     if (interstitial.IsLoaded())
     {
         interstitial.Show();
     }
 }

 using UnityEngine;
 using GoogleMobileAds.Api;

 public class Ads : MonoBehaviour
 {
     void Start()
     {
         BannerView adsObject = new BannerView(
                 "MY ADS ID", AdSize.SmartBanner, AdPosition.Bottom);
         AdRequest getAds = new AdRequest.Builder().Build();
         adsObject.LoadAd(getAds);
         }
 }