Fog service can't join server

[Pogpog]

Hello,

I can’t rename my computer, actualy every services seems to not join the server

fog.log :

28/03/2014 12:03 FOG::HostnameChanger Failed to connect to fog server!
28/03/2014 12:03 FOG::HostnameChanger Le délai d’attente de l’opération a expiré.
28/03/2014 12:03 FOG::HostnameChanger à System.Net.WebClient.DownloadDataInternal(Uri address, >WebRequest& request)
à System.Net.WebClient.DownloadString(Uri address)
à System.Net.WebClient.DownloadString(String address)
à FOG.HostNameChanger.changeHostName()
28/03/2014 12:03 FOG::HostnameChanger Sleeping for 1 minute.

when i capture trafic from the computeri have frams like this :
9300.666947000 10.49.2.108 YYY.YYY.YYY.YYY HTTP 205 GET [url]http://10.49.2.20/fog/service/servicemodule-active.php?mac=00:21:9B:6F:FA:3B|00:21:9B:6F:FA:3B&moduleid=dircleanup[/url] HTTP/1.1

where :
10.49.2.108
10.49.2.20 is the fog server address
YYY.YYY.YYY.YYY is the proxy server address.

the proxy server didn’t know the fog server (and i can’t modify it)
i can’t understand why the fog service asks the proxy server something.
Is there a parameter on my fog server to avoid this?

Sorry for my english.