android ics fading edges don't work

somehow fading edges seems not to work for android ics (android 4+) for own views. If I test this layout on a lower android version it paints the fading edge but not on android 4.1.

<FrameLayout
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"
    android:fadingEdge="vertical"
    android:focusableInTouchMode="true" <-- does not make any change
    android:focusable="true"           <--
/>

Is there any workaround?