Your MP-server doesn't respond. Have you setup port forwarding and correct firewall rules in your router? Otherwise other players can't see your MP server.
See topic "Can't get server to work" at http://forum.shipsim.com/index.php/topic,31383.msg403278.html#msg403278 (http://forum.shipsim.com/index.php/topic,31383.msg403278.html#msg403278) for instructions ho to properly set-up any public MP server. Think about portforwarding in your internet router, etc.
http://www.mediafire.com/file/s86d5ahjh3r94er/Private_server_or_Manual_connection.pdf (http://www.mediafire.com/file/s86d5ahjh3r94er/Private_server_or_Manual_connection.pdf)
http://www.mediafire.com/download/2r6a4fzces82xj6/Sky-SSE.pdf (http://www.mediafire.com/download/2r6a4fzces82xj6/Sky-SSE.pdf)
