problems with implementing Admob banner ads

Hi.

I followed this tutorial code. it says that there's supposed to be a little pop up where the banner is programmed to be, but its not popping up after I build and run it on android devices. When I run it I get a notification on the log of:

Dummy .ctor Dummy Createbannerview Dummy LoadAd

Any and all help would be appreciated.

using GoogleMobileAds.Api;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AdScript : MonoBehaviour {

 // Use this for initialization
 void Start () {    

     showBannerAd();    

 }

 private void showBannerAd()     
 {
     string adID = "ca-app-pub-***********";    

     //***For Testing in the Device***
     AdRequest request = new AdRequest.Builder()    
         .AddTestDevice(AdRequest.TestDeviceSimulator)           // Simulator.
         .AddTestDevice("***********")  // My test device.
         .Build();    

     //***For Production When Submit App***
     //AdRequest request = new AdRequest.Builder().Build();    

     BannerView bannerAd = new BannerView(adID, AdSize.SmartBanner, AdPosition.Bottom);    
     bannerAd.LoadAd(request);    
 }

 // Update is called once per frame
 void Update () {    

 }    

}