Admob test ad working but not real ad

Question

I added everything to android application as per the instructions from the admob website. On both the emulator and phone i tested my app. The test ads were displaying properly. i generated a signed apk and still it is showing the test ads. what should i do? here my code:

 <com.google.android.gms.ads.AdView
    android:id="@+id/adView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_alignParentBottom="true"
    ads:adSize="BANNER"
    ads:adUnitId="@string/banner_ad_unit_id">
</com.google.android.gms.ads.AdView>

in MainActivity:

 MobileAds.initialize(getApplicationContext(), "ca-app-pub-9815982880222619/9339487889");

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

Please help me!