private void cacheAdClicked()
    {
        if (adIsCahced)
        {
            MessageText.text = "Ad already cached!";
            return;
        }

        // its a good idea to cache ads when the level starts, then show it when the level ends
        MessageText.text = "Caching Ad...";
        ad.Cache();
    }
 private void showAdClicked()
 {
     // its a good idea to cache ads when the level starts, then show it when the level ends
     ad.Cache();
 }