Android : Ad finished loading in DFP banner Ad view in android

Hi I have DFP Ad Unit Id that have been using for DFP Banner Ad in both Phone and Tablet. i can see the ad in phone at the banner ad with size of smartBanner but i could not see any ad in Tablet and i got message only like "Ad finished loading".

I have used two different Ad unit id for phone and tablet and Ad size also that mean i am using AdSize.SMART_BANNER for Phone and new AdSize(Constants.getScreenWidhth(), 50) for Tablet devices

My Code Part is

adView = new PublisherAdView(this);

    actvity = AlbumsListActivity.this;
    // Find out the Device either Phone or Tablet
            String deviceType = Constants.screenSizeFindOut(actvity);

            String Tag = "AlbumsListActivity";
            if(deviceType.equals("tablet")){

                Log.i(Tag ,
                        "Google Admob Id for tablet: "
                                + this.getResources().getString(
                                        R.string.GoogleAdMob_TabletadUnitId));
                adView.setAdUnitId(this.getResources().getString(
                        R.string.GoogleAdMob_TabletadUnitId));


                adView.setAdSizes(new AdSize(Constants.getScreenWidhth(), 50));

            }
            else if(deviceType.equals("phone")){
                Log.i(Tag,
                        "Google Admob Id for phone: "
                                + this.getResources().getString(
                                        R.string.GoogleAdMob_PhoneadUnitId));
                adView.setAdUnitId(this.getResources().getString(
                        R.string.GoogleAdMob_PhoneadUnitId));

                adView.setAdSizes(AdSize.SMART_BANNER);

            }
            else
                ;

public static String screenSizeFindOut(Activity mContext){
    DisplayMetrics metrics = new DisplayMetrics();
    mContext.getWindowManager().getDefaultDisplay().getMetrics(metrics);

    widthPixels = metrics.widthPixels;
    heightPixels  = metrics.heightPixels;

    Log.d("" + mContext.getLocalClassName(), "Width and Height of the screen :"+widthPixels+ "/" + heightPixels );

    float scaleFactor = metrics.density;
    float widthDp = widthPixels / scaleFactor;
    float heightDp = heightPixels / scaleFactor;

    float smallestWidth = Math.min(widthDp, heightDp);

    if (smallestWidth > 720) {
        //Device is a 10" tablet
        return "tablet";
    } 
    else if (smallestWidth > 600) {
        //Device is a 7" tablet
        return "tablet";
    }
    else
        return "phone";

}

public static int getScreenWidhth(){
    return widthPixels;
}

Please help me if some one got solution for this