title: Android elevation of View in CardView is not shown
body: <p>I have a RelativeLayout inside a CardView that i want to elevate in Android Lollipop but the elevation is not shown (the shadow is not shown):</p>
  
  <p><img src="https://i.stack.imgur.com/W4O38.jpg" alt="enter image description here"></p>
  
  <p>My layout file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:android.support.v7.cardview="http://schemas.android.com/apk/res-auto"
      style="@style/CardViewStyle"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:elevation="5dp"
      android:orientation="horizontal"
      android.support.v7.cardview:cardElevation="5dp"&gt;
  
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:background="@drawable/list_selector"
      android:paddingBottom="5dp"&gt;
  
      &lt;ImageView
          android:id="@+id/article_thumb"
          android:layout_width="match_parent"
          android:layout_height="150dp"
          android:layout_alignParentTop="true"
          android:contentDescription="@string/app_name"
          android:scaleType="centerCrop" /&gt;
  
      &lt;TextView
          android:id="@+id/article_title"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_below="@+id/article_thumb"
          android:layout_marginEnd="10dp"
          android:layout_marginLeft="10dp"
          android:layout_marginRight="10dp"
          android:layout_marginStart="10dp"
          android:ellipsize="middle"
          android:linksClickable="false"
          android:longClickable="false"
          android:text="@string/title"
          android:textAppearance="@style/TextAppearance.AppCompat.Title"
          android:textColor="@color/black" /&gt;
  
      &lt;TextView
          android:id="@+id/article_date"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_alignLeft="@+id/article_title"
          android:layout_alignStart="@+id/article_title"
          android:layout_below="@+id/article_title"
          android:layout_marginTop="10dp"
          android:text="@string/date"
          android:textAppearance="@style/TextAppearance.AppCompat.Light.Widget.PopupMenu.Small"
          android:textColor="@color/gray" /&gt;
  
      &lt;RelativeLayout
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_alignEnd="@+id/article_title"
          android:layout_alignRight="@+id/article_title"
          android:layout_below="@+id/article_title"
          android:layout_marginTop="10dp"
          android:elevation="30dp"
          android:translationZ="30dp"&gt;
  
          &lt;ImageView
              android:id="@+id/redbubble"
              android:layout_width="25dp"
              android:layout_height="25dp"
              android:layout_gravity="center"
              android:contentDescription="@string/app_name"
              android:scaleType="centerCrop"
              android:src="@drawable/redbubble" /&gt;
  
          &lt;TextView
              android:id="@+id/article_comment_bubble"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_alignParentTop="true"
              android:layout_centerHorizontal="true"
              android:textAppearance="@style/TextAppearance.AppCompat.Small"
              android:textColor="@color/white" /&gt;
      &lt;/RelativeLayout&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p></p>
  
  <p>So inside this layout I added this two lines to the RelativeLayout to make the elevation:</p>
  
  <pre><code>android:elevation="30dp"
  android:translationZ="30dp"
  </code></pre>
  
  <p>Anyone an idea why it is not shown? At the moment I test it with a Emulator using Android API 21 (Lollipop).</p>