Android:elevation not working

I'm have to develop an android wear application, and Android:elevation in activity not showing a shadow.

XML Code of activity -

<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    tools:deviceIds="wear_round"
    android:id="@+id/round_activity_main"
    style="@style/AppTheme"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true">

    <FrameLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true"
        android:id="@+id/frameLayout"
        android:elevation="10sp"
        android:layout_alignParentEnd="true">

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="40sp"
            android:gravity="center"
            android:maxLines="2"
            android:id="@+id/tvResult"
            android:textStyle="bold"
            android:text=""
            android:fontFamily="sans-serif-light"
            style="@style/AppTheme"
            android:layout_marginLeft="40sp"
            android:layout_marginRight="40sp"
            android:layout_marginTop="20dp" />

    </FrameLayout>

    <android.support.v4.view.ViewPager
        xmlns:android="http://ift.tt/nIICcg"
        android:id="@+id/pagerRound"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        style="@style/AppTheme"
        android:layout_below="@+id/frameLayout" />

</RelativeLayout>

In the preview shadow displayed, in the emulator no shadows