Hi Alessandro,
Actually I'm getting a 404 from the sample code as well. I was getting a 407 because our security implemented a proxy (WebWasher) and I'm supplying the credentials like so:
service.Proxy =
new System.Net.WebProxy(http://ourproxyserver, true, null, new System.Net.NetworkCredential("MyLoginName", "MyLoginPass", "OurDomain.com"));
// Send the request; display the response.
SearchResponse response = service.Search(request);
*Edit
Turns out I has the wrong IP for the proxy.
Our connections tab in Internat Options is disabled but you can find you proxy settings
in the registry at HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
Thanks,
Brent