Use of WebDAV to access OWA (exchange 2003) mails with Basic authentication and SSL

Question

I have got a working C# code for accessing OWA mails using WebDAV against a FBA enabled exchange 2003 (http://support.microsoft.com/kb/891748/en-us/)

But my client's OWA (exchange 2003) has Basic authentication and SSL (i-e when I try to access the web mail link through browser I get a grey login box instead of a web page I can log into the mail box once I enter the correct details) But my same fails with a 401 error against this mailbox.

I got the simple request working for the Basic authentication using –

String usernamePassword = strUserName + ":" + strPassword;
WebReq.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(new ASCIIEncoding().GetBytes(usernamePassword)));

But the subsequent WebDAV SEARCH request fails with 404 (resource not found) error.

Can we use WebDAV against an exchange 2k3 with SSL and Basic authentication?