@jason-mccreary is totally right. Besides I recommend you this code to get more info in case of malfunction:
$rest = curl_exec($crl);
if ($rest === false)
{
// throw new Exception('Curl error: ' . curl_error($crl));
print_r('Curl error: ' . curl_error($crl));
}
curl_close($crl);
print_r($rest);
EDIT 1
To debug you can set CURLOPT_HEADER to true to check HTTP response with firebug::net or similar.
curl_setopt($crl, CURLOPT_HEADER, true);
EDIT 2
About Curl error: SSL certificate problem, verify that the CA cert is OK try adding this headers (just to debug, in a production enviroment you should keep these options in true):
curl_setopt($crl, CURLOPT_SSL_VERIFYHOST, false);
curl_setopt($crl, CURLOPT_SSL_VERIFYPEER, false);