How the custom the ActionBar by using xml in Android?

I am try to custom the ActionBar by using xml in Android.

The actionbat.xml is like the following:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout  xmlns:android="http://ift.tt/nIICcg"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/bar_background" >

    <ImageView 
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/bar_icon"/>    

</RelativeLayout >

And I using the following code to set ActionBar in Fragment

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.function_list, container, false) ;

        ActionBar bar = getActivity().getActionBar();
        bar.setCustomView(R.layout.actionbar);

But the ActionBar didn't change anything , did I missing something ?

Thanks in advance.