Windows client: Connection Could not be opened: A network error occurred

Dear friends,
I install a Webissues server on a shared hosting as subdomain:
h t-t p :// b u g s DOT intrust DOT co.il
I'm running only one Webissues server.
I can connect without any problem with the Web client.

I downloaded the Webissues Desktop Client X86 and install it on several Windows XP clients, but I cannot login.
After I'm entering the URL address the client prompt me to enter a username and password. I tried to login but I'm getting an error message:
Connection Could not be opened: A network error occurred.

I ran a tcpdump on the server and there is no traffic from client to server afrer enter username and password (from several client).
I ran Wireshark on one of the client and there is no traffic too from client to server after entering username and password.
Please see the screenshuts:
http://desmond.imageshack.us/Himg542/scaled.php?server=542&filename=001xho.jpg&res=landing
http://desmond.imageshack.us/Himg339/scaled.php?server=339&filename=002myj.jpg&res=landing

Any ideas?
Thanks,
Miki