title: Android elevation property not working
body: <p>Since upgrading to SDK 21 I've been trying to use the elevation property but it never seems to work.</p>
  
  <p>I want to elevate a frame above others so I'm setting the following</p>
  
  <pre><code>android:elevation="4dp"
  </code></pre>
  
  <p>but there's no sign of shadow. I've tried buttons and framelayouts but not got any elevation</p>
  
  <p>So here's the full tag</p>
  
  <pre><code>    &lt;FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:card_view="http://schemas.android.com/apk/res-auto"
      android:id="@+id/panel_card"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:background="#ffffff"
      android:elevation="4dp"
      &gt;
  </code></pre>
  
  <p>Am I missing something else I need to add</p>