soapUI 4.5 cant provide NTLM Auth. under vpn

Hi,

I am testing a WS which requires NTLM authentication. I have to connect to a VPN to access the WS. Once I connect to the vpn I check the endpoint via browser to confirm credentials are working. So far so good.

Afterwards I set up credentials and authorizaition type configuration in soapUI so I can proceed to test my request.

Every call on the WS operation will log the following message;
WARN:Authentication error: ntlm authorization challenge expected, but not found

Returning a blank response along with a 401 error on the http headers;
HTTP/1.1 401 Unauthorized
Content-Length: 0
Server: Microsoft-HTTPAPI/2.0
WWW-Authenticate: Negotiate
Date: Tue, 17 Jul 2012 13:12:16 GMT


Is there anything am I missing, or is soapUI's behaviour not correct?

I have already googled about soapUI's ntlm configuration and double checked every issue I found about it, yet I still cant connect despite providing correct configuration.

Thanks in advance,

Regards.

PD: I already checked this thread in case anyone is willing to point out: viewtopic.php?f=13&t=13141
But I think my issue is closer to soapUI's behaviour under VPN rather than the matter discussed in the previous thread.