Android + Card View shadow not showing in emulator 5.0?

I am using the new map support library and see support for the shadow version of the "snapshot" support on older devices. However, when I run the application in emulator 5.0, I cannot see the shadow. Any idea why?

    <android.support.v7.widget.CardView
        xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:id="@+id/card_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="0dp"
        app:cardBackgroundColor="#FFFFFFFF"
        app:cardCornerRadius="2dp"
        app:cardElevation="20dp"
        app:contentPadding="0dp" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TEXTVIEW" />
    </android.support.v7.widget.CardView>