When I try to connect to a proxy server with a php-script, everything works fine on my local computer. But when I try the same script on a webserver, a timeout-error occurs.

The script looks something like this:

<?php  $  username = ‚***********'; $  password = ‚*********'; $  port = 22225; $  session = mt_rand(); $  super_proxy = ‚*********'; $  curl = curl_init('http://lumtest.com/myip.json'); curl_setopt($  curl, CURLOPT_RETURNTRANSFER, 1); curl_setopt($  curl, CURLOPT_PROXY, "http://$  super_proxy:$  port"); curl_setopt($  curl, CURLOPT_PROXYUSERPWD, "$  username-country-de-session-$  session:$  password"); $  result = curl_exec($  curl); curl_close($  curl); if ($  result)    echo $  result; ?> 

What are possible obstacles, that are preventing the connection?