title: Android "elevation" not showing a shadow
body: <p>I have a ListView, and with each list item I want it to show a shadow beneath it. I am using Android Lollipop's new elevation feature to set a Z on the View that I want to cast a shadow, and am already doing this effectively with the ActionBar (technically a Toolbar in Lollipop). I am using Lollipop's elevation, but for some reason it isn't showing a shadow under the list items. Here is how each list item's layout is set up:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      android:orientation="vertical"
      style="@style/block"
      android:gravity="center"
      android:layout_gravity="center"
      android:background="@color/lightgray"
      &gt;
  
      &lt;RelativeLayout
          android:layout_width="300dp"
          android:layout_height="300dp"
          android:layout_marginLeft="40dp"
          android:layout_marginRight="40dp"
          android:layout_marginTop="20dp"
          android:layout_marginBottom="20dp"
          android:elevation="30dp"
          &gt;
  
          &lt;ImageView
              android:id="@+id/documentImageView"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:scaleType="centerCrop" /&gt;
  
          &lt;LinearLayout
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:background="@color/alphared"
              android:layout_alignParentBottom="true" &gt;
  
              &lt;appuccino.simplyscan.Extra.CustomTextView
                  android:id="@+id/documentName"
                  android:layout_width="match_parent"
                  android:layout_height="wrap_content"
                  android:textColor="@color/white"
                  app:typeface="light"
                  android:paddingLeft="16dp"
                  android:paddingTop="8dp"
                  android:paddingBottom="4dp"
                  android:singleLine="true"
                  android:text="New Document"
                  android:textSize="27sp"/&gt;
  
              &lt;appuccino.simplyscan.Extra.CustomTextView
                  android:id="@+id/documentPageCount"
                  android:layout_width="match_parent"
                  android:layout_height="wrap_content"
                  android:textColor="@color/white"
                  app:typeface="italic"
                  android:paddingLeft="16dp"
                  android:layout_marginBottom="16dp"
                  android:text="1 page"
                  android:textSize="20sp"/&gt;
  
          &lt;/LinearLayout&gt;
  
      &lt;/RelativeLayout&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>However, here is how it shows the list item, without a shadow:
  
  <img src="https://i.stack.imgur.com/lo95C.png" alt="enter image description here">
  </p>
  
  <p>I have also tried the following to no avail:</p>
  
  <ol>
  <li>Set the elevation to the ImageView and TextViews themselves instead of the parent layout.</li>
  <li>Applied a background to the ImageView.</li>
  <li>Used TranslationZ in place of Elevation.</li>
  </ol>