Required xml attribute adsize was missing

I try to add Admob in live wallpaper setting, but it shows "required xml attribute adsize was missing". I tried many methods that i seached in internet, but this methods don't solve a problem((( How to solve this problem< who know?

AdMobPreference.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://ift.tt/nIICcg"
    xmlns:ads="http://ift.tt/1bhZ3VK"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
  <com.google.android.gms.ads.AdView 
      android:id="@+id/adView"
                         android:layout_width="wrap_content"
                         android:layout_height="wrap_content"
                         ads:adUnitId="ca-app-pub-6437604595659430/1119994508"
                         ads:adSize="BANNER"/>
</LinearLayout>

AdmobPreference.java

public class AdmobPreference extends Preference
{

    public AdmobPreference(Context context) {
        super(context, null);
    }

    public AdmobPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected View onCreateView(ViewGroup parent) {
            //override here to return the admob ad instead of a regular preference display
        LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        return inflater.inflate(R.layout.admob_preference, null);
    }

}

prefs.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://ift.tt/nIICcg"
android:orderingFromXml="true">>
  <EditTextPreference android:key="number"
    android:title="Speed of PushUps"></EditTextPreference>  
    **<ter.trimf.body_b_pushups.AdmobPreference android:key="adView"/>**
</PreferenceScreen>