title: PHP if statement with isset not working
body: <p>I presumed this was easy code but this doesnt work as intended:</p>
  
  <pre><code>$id = $_GET['id'];
  if (!isset($id)){
      header("HTTP/1.1 404 not found");
      include("404.php");
  }
  else {
      include('includes/functions.php'); 
  }
  </code></pre>
  
  <p>So i've taken the get parameters off of the URL yet i dont receive a 404 error?</p>
  
  <p>Any ideas?</p>