Android : Android: Appcompat 21 how to add shadow on actionbar

I add the new material design actionbar from the new appcompat and I use the new toolbar widget. I set a custom background on the toolbar on xml but my problem is that the drop shadow from the actionbar is not displayed. Do you know how to do this?

Toolbar code

<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/my_awesome_toolbar"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:minHeight="?attr/actionBarSize"
    android:background="@drawable/ab_background_textured"
    app:theme="@style/MyTheme"
    app:popupTheme="@style/MyTheme.Popup"/>

MyTheme style

<style name="MyTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="android:textColorPrimary">@color/abc_primary_text_material_dark</item>
    <item name="actionMenuTextColor">@color/abc_primary_text_material_dark</item>
    <item name="android:textColorSecondary">#ffff8800</item>
</style>

MyTheme.Popup style

<style name="MyTheme.Popup" parent="ThemeOverlay.AppCompat.Dark">
    <item name="android:textColor">#ffffff</item>
</style>