http_post

Hi , I am trying the following code to send XML but get no response from the
server, can someone tell me what I am doing wrong? thank you.
<?php
function http_post($server, $port, $url, $vars) {
    // example:
    //  http_post(
    //  "www.fat.com",
    //  80,
    //  "/weightloss.pl",
    //  array("name" => "obese bob", "age" => "20")
    //  );

    $urlencoded = "";
    while (list($key,$value) = each($vars))
        $urlencoded.= urlencode($key) . "=" . urlencode($value) . "&";
        $urlencoded = substr($urlencoded,0,-1);
        $content_length = strlen($urlencoded);
        $headers = "POST $url HTTP/1.1
Accept:  text/plain, text/html, text/xml, image/gif, image/jpeg,
image/png, image/bmp
Accept-Charset: UTF-8
Accept-Language: en
Content-Length: $content_length
Cache-Control: no-cache
Content-Type: application/x-www-form-urlencoded
Host:  $server
User-Agent: Panasonic-GAD67/1.0 UP.Browser/5.0.3.5 (GUI)
Connection: Keep-Alive

";
        $fp = fsockopen($server, $port, $errno, $errstr);
        if (!$fp) {
            return false;
        }
        fputs($fp, $headers);
        fputs($fp, $urlencoded);

        $ret = "";
        while (!feof($fp))
            $ret.= fgets($fp, 1024);
        fclose($fp);
        return $ret;
}

$request="<barceloDS_requests><request type='destination list'
id='8'><language_code>ESP</language_code><agency><primary>888</primary><seco
ndary>88</secondary><detail>888</detail><branch>1</branch></agency></request
></barceloDS_requests>";

http_post("195.57.250.36",80,"/barceloDS/interface/xml/",array("xml"
=>$request));
?>