USPS 500 error

$req = "GET /ShippingAPI.dll?API=" . $apiName . "&XML=" . urlencode($XMLRequest) . " HTTP/1.1\r\n". 'Server: '.$_SERVER['SERVER_SOFTWARE']."\r\n". 'Host: production.shippingapis.com'."\r\n". 'Content-Type: text/xml'."\r\n". 'Accept: */'.'*'."\r\n". 'Connection: close'."\r\n\r\n";

HTTP/1.1 200 OK X-Backside-Transport: OK OK Connection: Keep-Alive Transfer-Encoding: chunked Date: Tue, 12 Nov 2013 03:32:52 GMT Server: Microsoft-IIS/6.0 X-Powered-By: ASP.NET X-Client-IP: 56.0.70.6 Content-Type: text/xml 27 <?xml version="1.0" encoding="UTF-8"?> 17c <RateV4Response><Package ID="1"><ZipOrigination>80923</ZipOrigination><ZipDestination>49426</ZipDestination><Pounds>1</Pounds><Ounces>0</Ounces><Container>VARIABLE</Container><Size>REGULAR</Size><Zone>6</Zone><Postage CLASSID="1"><MailService>Priority Mail 2-Day&amp;lt;sup&amp;gt;&amp;#8482;&amp;lt;/sup&amp;gt;</MailService><Rate>6.20</Rate></Postage></Package></RateV4Response> 0

function doUSPS($XMLRequest, $domesticShipment) { $apiName = 'RateV4'; // Change API name if this is an International shipment. // Determined by $domesticShipping boolean value. // if($domesticShipment == false) $apiName = 'IntlRateV2'; $url = 'http://production.shippingapis.com/ShippingAPI.dll?API=' . $apiName . '&XML=' . urlencode($XMLRequest); $session = curl_init(); curl_setopt($session, CURLOPT_FRESH_CONNECT, true); curl_setopt($session, CURLOPT_POST, false); curl_setopt($session, CURLOPT_FOLLOWLOCATION, false); curl_setopt($session, CURLOPT_FAILONERROR, true); curl_setopt($session, CURLOPT_RETURNTRANSFER, true); curl_setopt($session, CURLOPT_COOKIEFILE, ''); curl_setopt($session, CURLOPT_SSL_VERIFYPEER, false); curl_setopt($session, CURLOPT_SSL_VERIFYHOST, false); curl_setopt($session, CURLOPT_ENCODING, 'UTF-8'); curl_setopt($session, CURLOPT_URL, $url); $result = curl_exec($session); $error = curl_error($session); if(empty($result)) { $app = JFactory::getApplication(); $app->enqueueMessage( 'Cannot connect to USPS web service. You hosting company might be blocking outbound connections.<br/>'.$error); return false; } $responseDoc = simplexml_load_string($result); if($responseDoc === false) { $app = JFactory::getApplication(); $app->enqueueMessage('Cannot dialog with USPS web service.<br/>'.$result); return false; } return $responseDoc; }