title: PHP Session variable is set, but PHP doesn't see it. Very strange
body: <p>Okay, maybe this is because I've been coding for over 24 hours and my eyes are glazing over, but I'm stumped here. Why does this happen:</p>
  
  <pre>
  &lt;?php
  session_start();
  $tmp = "index";
  
  echo "A: " . $_SESSION['page_loaded']['index']; // returns 1
  echo "B: " . $_SESSION['page_loaded'][$tmp]; // is set, but is empty
  ?&gt;
  </pre>
  
  <p>I feel like I'm missing something very basic here but I don't know what.</p>