How to load interstitial ads in adview

I am referring this google tutorial to place interstitial ads in my app, https://developers.google.com/admob/android/interstitial.

I am able to successfully show banner ads in adview, but interstitial ads are not being shown. I am using the below code to load interstitial ads.

public class DashBoardFragment extends Fragment implements OnClickListener{

    private ViewPager pager;
    private ViewPagerAdapter adapter;
    private SlidingTabLayout tabs;
    private ArrayList<Thoughts_Model> list;
    private Isconnected checkinternet;
    private SessionManager session;
    private JSONObject json_data;
    private String userid = "", tag_json_arry = "json_array_req";
    private int index = 0;
    private TextView btn_favourite,btn_share;
    private LinearLayout progressBar_container;
    private OnPageChangeListener pageChangeListener;
    private LinearLayout add_container;
    private AdView mAdView;
    InterstitialAd interstitial;
    AdRequest adRequest;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v =inflater.inflate(R.layout.dashboard_fragment,container,false);
        this.session = new SessionManager(getActivity());

        userid = session.getuserid();
        checkinternet = new Isconnected(getActivity());

        mAdView = new AdView(getActivity());
        mAdView.setAdSize(Utility.getAdSize(getActivity()));
        mAdView.setAdUnitId(getResources().getString(R.string.banner_ad_unit_id));

        add_container = (LinearLayout)v.findViewById(R.id.add_container);

        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
        params.addRule(RelativeLayout.ALIGN_BOTTOM, RelativeLayout.TRUE); 
        add_container.addView(mAdView,params);

        adRequest = new AdRequest.Builder().build();
        mAdView.loadAd(adRequest);                 // this is loading banner ad in adview properly

        interstitial = new InterstitialAd(getActivity());
        interstitial.setAdUnitId(getResources().getString(R.string.banner_ad_unit_id));

        interstitial.setAdListener(new AdListener() {
            @Override
            public void onAdClosed() {
                requestNewInterstitial();
            }
        });

        requestNewInterstitial();

        progressBar_container = (LinearLayout) v.findViewById(R.id.progressBar_container);
        btn_favourite = (TextView) v.findViewById(R.id.btn_favourite);
        btn_share = (TextView) v.findViewById(R.id.btn_share);

        list = new ArrayList<Thoughts_Model>();
        pager = (ViewPager) v.findViewById(R.id.pager);
        pageChangeListener = new OnPageChangeListener() {
            @Override
            public void onPageScrollStateChanged(int arg0) { }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) { }

            @Override
            public void onPageSelected(int position) {

                index = position;
                if(list.get(position).getIsFavorite().equals("1")){
                    btn_favourite.setCompoundDrawablesWithIntrinsicBounds(R.drawable.ic_favorite_filled, 0, 0, 0);
                }else{
                    btn_favourite.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0);
                }
            }
        };
        pager.addOnPageChangeListener(pageChangeListener);

        tabs = (SlidingTabLayout) v.findViewById(R.id.tabs);
        tabs.setDistributeEvenly(true); 
        tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
            @Override
            public int getIndicatorColor(int position) {
                return getResources().getColor(R.color.colortabstrip);
            }
        });

        btn_favourite.setOnClickListener(this);
        btn_share.setOnClickListener(this);
        return v;
    }

    private void requestNewInterstitial() {
        // TODO Auto-generated method stub
        interstitial.loadAd(adRequest);
    }

    @Override
    public void onDestroy() {
        mAdView.pause();
        super.onDestroy();
    }

    @Override
    public void onResume() {
        super.onResume();
        mAdView.resume();
        AppController.getInstance().trackScreenView("Home Screen");
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.btn_favourite:
            if (checkinternet.isConnected()) {
                AddFavorite();
            } else {
                Utility.CommanDialog(getActivity(),
                        getResources().getString(R.string.try_again),
                        getResources().getString(R.string.no_internet), true);
            }
            break;

        case R.id.btn_share:
            //this is supposed to load ad but it toasts the message.
            if (interstitial != null && interstitial.isLoaded()) {
                interstitial.setAdListener(new AdListener(){
                      public void onAdLoaded(){
                          interstitial.show();
                      }
            });

            } else {
                Toast.makeText(getActivity(), "Ad failed to load", Toast.LENGTH_SHORT).show();
            }

            break;

        default:
            break;
        }
    }

    private List<Fragment> getFragments(){
        List<Fragment> fList = new ArrayList<Fragment>();
        for (int i = 0; i < list.size(); i++) {
            fList.add(ShowCategory.newInstance(list.get(i)));
        }
        return fList;
    }
}

below is the code for xml layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:ads="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:animateLayoutChanges="true"
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/container_toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <com.deadbrains.shareyourthought.commons.SlidingTabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:animateLayoutChanges="true"
            android:background="@color/colorPrimary"
            android:elevation="2dp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/progressBar_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/black_trans"
        android:gravity="center"
        android:orientation="horizontal" >

        <ProgressBar
            android:id="@+id/progressBar1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center" />
    </LinearLayout>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" >

        <android.support.v4.view.ViewPager
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:animateLayoutChanges="true" >
        </android.support.v4.view.ViewPager>
    </FrameLayout>

    <LinearLayout
        android:id="@+id/add_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="bottom"
        android:orientation="vertical" >

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <TextView
            android:id="@+id/btn_favourite"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="@color/colorPrimary"
            android:drawablePadding="-10dp"
            android:gravity="center"
            android:paddingBottom="15dp"
            android:paddingLeft="20dp"
            android:paddingRight="5dp"
            android:paddingTop="15dp"
            android:text="Favourite"
            android:textSize="16sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/btn_share"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="2dp"
            android:layout_weight="1"
            android:background="@color/colorPrimary"
            android:drawableLeft="@drawable/ic_share_white"
            android:drawablePadding="15dp"
            android:paddingBottom="15dp"
            android:paddingLeft="25dp"
            android:paddingRight="5dp"
            android:paddingTop="15dp"
            android:text="Share"
            android:textSize="16sp"
            android:textStyle="bold" />
    </LinearLayout>

</LinearLayout>

I've added ad activity in manifest as below,

<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>

There are no errors but ads are not showing. Where am I going wrong? please help.