URL and curl access different when accessing a web api

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PHP

cURL

URL and cURL access different when accessing a web aPI. Am I missing headers or something because the cURL php only outputs "''" rather than the URL output from below

What I have tried:

I have this URL access : http://bookings.seawings.ae/remoteconnect/default.asp?XML=%3Ccs%3E%0D%0A+%3Co+n%3D%22authenticationcode%22+v%3D%22d657cce7fa320a23950dca157fe693b8%22%2F%3E%0D%0A+%3Cc+n%3D%22flightsearch%22%3E%0D%0A++%3Cq+n%3D%22StartDate%22+v%3D%2211-Apr-2012%22%2F%3E%0D%0A++%3Cq+n%3D%22EndDate%22+v%3D%2211-Apr-2014%22%2F%3E%0D%0A++%3Cq+n%3D%22Typeofflight%22+v%3D%22SILVER%22%2F%3E%0D%0A++%3Cq+n%3D%22Seats_Adult%22+v%3D%228%22%2F%3E%0D%0A+%3C%2Fc%3E%0D%0A%3C%2Fcs%3E
and it returns :
<cs> <c n="flightsearch">
but when I try to run it in PHP:

<?php $request_xml = '<cs> <o n="authenticationcode" v="d657cce7fa320a23950dca157fe693b8"/> <c n="FlightSearch"> <q n="StartDate" v="1-Jul-2013"/> <q n="EndDate" v="30-Jul-2013"/> <q n="Seats_adult" v="3"/> </c> </cs>';
$ch = curl_init(); curl_setopt($ch, CURLOPT_URL, 'https://bookings.seawings.ae/remoteconnect/default.asp'); //curl_setopt($ch, CURLOPT_USERPWD, $username.':'.$password); curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch, CURLOPT_SSLVERSION, 3); curl_setopt($ch, CURLOPT_TIMEOUT, 4); curl_setopt($ch, CURLOPT_POSTFIELDS, $request_xml); curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: close')); $result = curl_exec($ch);
echo stripslashes($result);
curl_close($ch);
?>

it only returns: "''"
I tried using Curl. Am I missing headers or something?