title: PayPal PDT and no transaction token returned
body: <p>I'm trying to get pdt data back from paypal sandbox, seems pretty straightforward but I don't get any data actually.
  I'm able to call the service and get the callback but there is no data.</p>
  
  <p>I'm following this example:
  <a href="https://github.com/paypal/pdt-code-samples/blob/master/paypal_pdt.php" rel="nofollow noreferrer">https://github.com/paypal/pdt-code-samples/blob/master/paypal_pdt.php</a></p>
  
  <p>and also did set my <em>selling tools settings</em> specifying:</p>
  
  <ul>
  <li>Auto return: on</li>
  <li>Payment Data Transfer: on</li>
  </ul>
  
  <p>The main issue is the transaction token, the line below has no value</p>
  
  <pre><code>$tx_token = $_GET['tx'];
  </code></pre>
  
  <p>Do I need some specific configuration on my server or what else I'm missing here?
  Should I use IPN?</p>
  
  <p>Thanks</p>