Admob banner is not showing

I have a game that I am trying to add ad banners to it, I have add the necessary manifest and code to do so but when i run it nothing shows up and I have no errors. Please help.

ad code

 using UnityEngine;
 using System.Collections;
 using GooglePlayGames;
 using UnityEngine.SocialPlatforms;

 public class Ads : MonoBehaviour {

 private const string AD_Unit_ID = "ca-app-pub-416510********39/3648529009";
 private AdMobPlugin admob;
 public void Awake()
 {
     DontDestroyOnLoad (this);
 }
 void Start () {
     admob = GetComponent<AdMobPlugin> ();
     admob.CreateBanner (AD_Unit_ID, AdMobPlugin.AdSize.SMART_BANNER, true,"",false);
     admob.RequestAd ();
     admob.ShowBanner ();
 }
 

 }

AdMobPlugin

 using System;
 using UnityEngine;

 public sealed class AdMobPlugin : MonoBehaviour {

 private const string CLASS_NAME = "com.nabrozidhs.admob.AdMob";

 private const string CALL_SHOW_BANNER = "showBanner";
 private const string CALL_HIDE_BANNER = "hideBanner";
 private const string CALL_SHOW_INSTERTITIAL = "showInterstitial";
 private const string CALL_REQUEST_AD = "requestAd";
 private const string CALL_REQUEST_INTERSTITIAL = "requestInterstitial";

 public enum AdSize {BANNER, MEDIUM_RECTANGLE, FULL_BANNER, LEADERBOARD, SMART_BANNER};

 public static event Action AdClosed = delegate{};
 public static event Action AdFailedToLoad = delegate{};
 public static event Action AdLeftApplication = delegate{};
 public static event Action AdLoaded = delegate{};
 public static event Action AdOpened = delegate{};

 public static event Action InterstitialClosed = delegate{};
 public static event Action InterstitialFailedToLoad = delegate{};
 public static event Action InterstitialLeftApplication = delegate{};
 public static event Action InterstitialLoaded = delegate{};
 public static event Action InterstitialOpened = delegate{};
 
 #if UNITY_ANDROID && !UNITY_EDITOR
 private AndroidJavaObject plugin;
 #endif
 
 /// <summary>
 /// Bind this instance.
 /// </summary>
 public void CreateBanner(string adUnitId, AdSize adSize, bool isTopPosition=true, string        interstitialId="", bool isTestDevice=false) {
     if (String.IsNullOrEmpty(interstitialId)) {
         interstitialId = "";
     }

  #if UNITY_ANDROID && !UNITY_EDITOR
     plugin = new AndroidJavaObject(
         CLASS_NAME,
         new AndroidJavaClass("com.unity3d.player.UnityPlayer")
             .GetStatic<AndroidJavaObject>("currentActivity"),
         adUnitId,
         adSize.ToString(),
         isTopPosition,
         interstitialId,
         gameObject.name,
             isTestDevice);
 #endif
 }

 /// <summary>
 /// Requests a banner ad. This method should be called
 /// after we have created a banner.
 /// </summary>
 public void RequestAd() {
 #if UNITY_ANDROID && !UNITY_EDITOR
     if (plugin != null) {
         plugin.Call(CALL_REQUEST_AD, new object[0]);
     }
 #endif
 }
 
 /// <summary>
 /// Requests an interstitial ad.
 /// </summary>
 public void RequestInterstitial() {
 #if UNITY_ANDROID && !UNITY_EDITOR
     if (plugin != null) {
         plugin.Call(CALL_REQUEST_INTERSTITIAL, new object[0]);
     }
 #endif
 }

 /// <summary>
 /// Shows the banner to the user.
 /// </summary>
 public void ShowBanner() {
 #if UNITY_ANDROID && !UNITY_EDITOR
     if (plugin != null) {
         plugin.Call(CALL_SHOW_BANNER, new object[0]);
     }
 #endif
 }

 /// <summary>
 /// Hides the banner from the user.
 /// </summary>
 public void HideBanner() {
 #if UNITY_ANDROID && !UNITY_EDITOR
     if (plugin != null) {
         plugin.Call(CALL_HIDE_BANNER, new object[0]);
     }
 #endif
 }

 /// <summary>
 /// Shows the interstitial ad to the user.
 /// </summary>
 public void ShowInterstitial() {
 #if UNITY_ANDROID && !UNITY_EDITOR
     if (plugin != null) {
         plugin.Call(CALL_SHOW_INSTERTITIAL, new object[0]);
     }
 #endif
 }

 public void OnAdClosed() {
     AdClosed();
 }

 public void OnAdFailedToLoad() {
     AdFailedToLoad();
 }

 public void OnAdLeftApplication() {
     AdLeftApplication();
 }

 public void OnAdLoaded() {
     AdLoaded();
 }

 public void OnAdOpened() {
     AdOpened();
 }

Android Manifest

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"      android:installLocation="preferExternal" package="com.example.admobtest" android:versionName="1.0"    android:versionCode="1">
 <supports-screens android:smallScreens="true" android:normalScreens="true"     android:largeScreens="true" android:xlargeScreens="true" android:anyDensity="true" />
   <uses-permission android:name="android.permission.INTERNET"/>
 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>    
 <uses-permission android:name="android.permission.INTERNET" />
 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 <application android:icon="@drawable/app_icon" android:label="@string/app_name"  android:debuggable="true">
 <meta-data android:name="com.google.android.gms.version"
        android:value="@integer/google_play_services_version" />    <meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" />
  <activity android:name="com.unity3d.player.UnityPlayerProxyActivity"  android:label="@string/app_name"  android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen">
   <meta-data android:name="unityplayer.ForwardNativeEventsToDalvik" android:value="true" />
   <intent-filter>
     <action android:name="android.intent.action.MAIN" />
     <category android:name="android.intent.category.LAUNCHER" />
   </intent-filter>
 </activity>
 <activity android:name="com.unity3d.player.UnityPlayerActivity" android:label="@string/app_name" android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen">
 </activity>
 <activity android:name="com.unity3d.player.UnityPlayerNativeActivity" android:label="@string/app_name" android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen">
   <meta-data android:name="unityplayer.ForwardNativeEventsToDalvik" android:value="true" />
   <meta-data android:name="android.app.lib_name" android:value="unity" />
 </activity>
 <activity android:name="com.unity3d.player.VideoPlayer" android:label="@string/app_name" android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen">
 </activity>
 <activity android:name="com.google.android.gms.ads.AdActivity"
       android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"
       android:theme="@android:style/Theme.Translucent" />
 <activity android:name="com.google.android.gms.ads.AdActivity" android:label="@string/app_name" android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen">
 </activity>
 <activity android:name="com.facebook.unity.FBUnityLoginActivity" android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen" android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen">
 </activity>
 <activity android:name="com.facebook.LoginActivity" android:configChanges="keyboardHidden|orientation" android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen">
 </activity>
 <activity android:name="com.facebook.unity.FBUnityDeepLinkingActivity" android:exported="true">
 </activity>
 <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="\ 694764773973338&#xA;" />
 </application>
 <uses-feature android:glEsVersion="0x00020000" />
 <uses-sdk android:minSdkVersion="9" android:targetSdkVersion="19" />
 </manifest>