void Start()
    {
        singleton = this;

        // bind button events
        CacheAdButton.Select();
        CacheAdButton.onClick.AddListener(cacheAdClicked);
        ShowAdButton.onClick.AddListener(showAdClicked);
        BackButton.onClick.AddListener(backClicked);

        // make sure we don't init the same Ad twice
        if (created)
        {
            return;
        }
        created = true;

        // create add
        var desc = new InterstitialAdDesc();

        // Global
        desc.Testing            = true;
        desc.EventCallback      = eventCallback;
        desc.UseClassicGUI      = false;
        desc.GUIOverrideEnabled = false;
        desc.UnityUI_SortIndex  = 1001;

        // WinRT (Windows 8.0 & 8.1)
        desc.WinRT_AdAPI = InterstitialAdAPIs.AdDuplex;        // NOTE: If building for WP 8.1 or Universal targets this value is used. All other WinRT values or used for Win8
        // NOTE: Currently no Win8 interstisial API are supported.

        // WP8 (Windows Phone 8.0 & 8.1)
        desc.WP8_AdAPI        = InterstitialAdAPIs.AdMob; // NOTE: If building for WP 8.1 or Universal targets this value is NOT used (Use the WinRT value instead). All other WP8 values are still used for WP 8.0, 8.1 and Universal.
        desc.WP8_AdMob_UnitID = "";                       // NOTE: Must set event for testing

        desc.WP8_AdDuplex_ApplicationKey = "";            // NOTE: Must set event for testing
        desc.WP8_AdDuplex_UnitID         = "";            // NOTE: Must set event for testing

        // iOS
        desc.iOS_AdAPI        = InterstitialAdAPIs.AdMob;
        desc.iOS_AdMob_UnitID = "";        // NOTE: Must set event for testing

        // Android
                #if AMAZON
        desc.Android_AdAPI = InterstitialAdAPIs.Amazon;
                #else
        desc.Android_AdAPI = InterstitialAdAPIs.AdMob;
                #endif
        desc.Android_AdMob_UnitID          = ""; // NOTE: Must set event for testing
        desc.Android_Amazon_ApplicationKey = ""; // NOTE: Must set event for testing

        // create ad
        ad = InterstitialAdManager.CreateAd(desc, createdCallback);
    }
    void Start()
    {
        // bind button events
        ShowAdButton.Select();
        ShowAdButton.onClick.AddListener(showAdClicked);
        BackButton.onClick.AddListener(backClicked);

        // make sure we don't init the same Ad twice
        if (created)
        {
            return;
        }
        created = true;

        // create add
        var desc = new InterstitialAdDesc();

        // Global
        desc.Testing            = true;
        desc.EventCallback      = eventCallback;
        desc.UseClassicGUI      = false;
        desc.GUIOverrideEnabled = false;
        desc.UnityUI_SortIndex  = 1001;

        // WP8
        desc.WP8_AdAPI        = InterstitialAdAPIs.AdMob;
        desc.WP8_AdMob_UnitID = "";        // NOTE: Must set event for testing

        // iOS
        desc.iOS_AdAPI        = InterstitialAdAPIs.AdMob;
        desc.iOS_AdMob_UnitID = "";        // NOTE: Must set event for testing

        // Android
                #if AMAZON
        desc.Android_AdAPI = InterstitialAdAPIs.Amazon;
                #else
        desc.Android_AdAPI = InterstitialAdAPIs.AdMob;
                #endif
        desc.Android_AdMob_UnitID          = ""; // NOTE: Must set event for testing
        desc.Android_Amazon_ApplicationKey = ""; // NOTE: Must set event for testing

        // create ad
        ad = InterstitialAdManager.CreateAd(desc, createdCallback);
    }