title: why is my header("Location: $_SERVER['HTTP_REFERER']"); PHP function not working?
body: <p>It works when I input </p>
  
  <pre><code>header("Location: http://www.google.com");
  </code></pre>
  
  <p>but it doesn't work when I have</p>
  
  <pre><code>header("Location: $_SERVER['HTTP_REFERER']");
  </code></pre>
  
  <p>I want to redirect the page to whatever page it came from.</p>