title: notify_url is not getting called
body: <p>every time im starting using PayPal ipn and stuff im getting stuck and my code isn't working.</p>
  
  <p>So today my problem is my ipn doesn't get called, and that's funny cause actually its was working 2 days ago.</p>
  
  <p>my form (button) :</p>
  
  <pre><code>require ('../init.php');
  
  if(!$_GET['id'] || !$userfunc-&gt;IsPlanIDExist($_GET['id']))
  {
    return;
  }
  
  $array = $userfunc-&gt;GetPlanArray($_GET['id']);
  
  ?&gt;
  &lt;form name="myform" action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post"&gt;
      &lt;input type="hidden" name="business" value="&lt;?=$userfunc-&gt;GetSitePayPal()?&gt;" /&gt;
      &lt;input type="hidden" name="notify_url" value="&lt;?=$userfunc-&gt;GetSiteURL()?&gt;core/php/paypal/checkpayment.php" /&gt;
      &lt;input type="hidden" name="cancel_return" value="&lt;?=$userfunc-&gt;GetSiteURL()?&gt;" /&gt;
      &lt;input type="hidden" name="return" value="&lt;?=$userfunc-&gt;GetSiteURL()?&gt;" /&gt;
      &lt;input type="hidden" name="rm" value="2" /&gt;
      &lt;input type="hidden" name="lc" value="" /&gt;
      &lt;input type="hidden" name="no_shipping" value="1" /&gt;
      &lt;input type="hidden" name="no_note" value="1" /&gt;
      &lt;input type="hidden" name="currency_code" value="USD" /&gt;
      &lt;input type="hidden" name="page_style" value="paypal" /&gt;
      &lt;input type="hidden" name="charset" value="utf-8" /&gt;
      &lt;input type="hidden" name="item_name" value="&lt;?=$array['name']?&gt;" /&gt;
      &lt;input type="hidden" name="cbt" value="&lt;?=$array['name']?&gt;" /&gt;
      &lt;input type="hidden" value="_xclick" name="cmd"/&gt;
      &lt;input type="hidden" name="amount" value="&lt;?=$array['price']?&gt;" /&gt;
      &lt;input type="hidden" name="custom" value="&lt;?php echo $array['id']?&gt;"/&gt;
      &lt;script type="text/javascript"&gt;
          document.myform.submit();
      &lt;/script&gt;
    &lt;/form&gt;
  </code></pre>
  
  <p>when I check the source everything is okay and should be working fine as it was.
  but today when I checked my purchase again it's not working and 2 days ago it was working fine, I didn't touch my system at all.</p>
  
  <p>Im using PayPal ipn code example from the GitHub so anything should be working fine.</p>