My app was suspended due to an issue with ads

today Google suspended my app saying that my ads violated Google TOS but I don't know what did it actually violate. I think there might be something wrong with my code structure i guess because I tried publishing it two times and in both it got suspended.

In my app I am using a View Pager and inside it I have 4 tabs. So the ads are placed in the View Pager as below

<LinearLayout xmlns:android="http://ift.tt/nIICcg"
xmlns:app="http://ift.tt/GEGVYd"
android:id="@+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="bottom"
android:orientation="vertical" >

<android.support.v4.view.ViewPager
    android:id="@+id/pager"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1" />

<com.google.android.gms.ads.AdView
    xmlns:ads="http://ift.tt/GEGVYd"
    android:id="@+id/adView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:adSize="SMART_BANNER"
    app:adUnitId="@string/banner_ad_unit_id" >
</com.google.android.gms.ads.AdView>

and the code in the View Pager activity

mAdView = (AdView) findViewById(R.id.adView);
 AdRequest adRequest = new AdRequest.Builder().build();
    mAdView.loadAd(adRequest);

I would be very thankful if someone told me the reason behind the continuous suspension.