admob interstitial not showing with google play services?

I'm trying to upgrade to google play services Admob version, However i can't seem to find the right way to show interstitial ads after trying for a few days, banner views seem to be displayed fine, its only the interstitial that's a problem.

This is my current code after referencing the google play services.

private InterstitialAd interstitial;



  public void onCreate(Bundle savedInstanceState)
  {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        AdView adView = (AdView)this.findViewById(R.id.adView);
        AdRequest adRequest = new AdRequest.Builder()
            .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
            .addTestDevice("TEST_DEVICE_ID")
            .build();
        adView.loadAd(adRequest);



        // Create the interstitial.
        interstitial = new InterstitialAd(this);
        interstitial.setAdUnitId("XXXXXXXXXXXXXXXXXXX");

        // Create ad request.
        AdRequest adRequestIN = new AdRequest.Builder().build();

        // Begin loading your interstitial.
        interstitial.loadAd(adRequestIN);


      }



    // Invoke displayInterstitial() when you are ready to display an interstitial.
    public void displayInterstitial() {
      if (interstitial.isLoaded()) {
        interstitial.show();
      }
    }

Banners are showing normally, interstitial nothing and there is nothing significant in the log cat either. thanks

    <?xml version="1.0" encoding="utf-8"?>

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
    <supports-screens android:smallScreens="true"
    android:normalScreens="true" android:largeScreens="true"
    android:anyDensity="true" />
                    <uses-permission android:name="android.permission.INTERNET"/>
                    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>




    <application
        android:allowBackup="true"
        android:icon="@drawable/logo"
        android:label="@string/app_name"
        android:theme="@style/AppTheme"
        android:hardwareAccelerated="true"
         >



       <activity android:name="com.google.android.gms.ads.AdActivity"
    android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"
    android:theme="@android:style/Theme.Translucent"/>
<meta-data android:name="com.google.android.gms.version"
           android:value="@integer/google_play_services_version"
           />