Problem with Google calendar API

I can't figure out why this code:

Code:

---

            try

            {

                // Authenticate

                CalendarService calService = new CalendarService("cl");

                                string name = (hidden); 

                                string pass = (hidden);

                calService.setUserCredentials(name, pass);

                                string token = calService.QueryAuthenticationToken();

---

works fine (token is a valid Google authorization token) under Windows but on Mono token always comes back as null.

I am using the same Google .DLLs on both systems (in fact, it's the same PC with Windows Vista/Ubuntu dual-boot).

This is driving me crazy... it always works, I can read/write calendar items all day long under Windows but the same code running on Mono on Ubuntu will not authenticate. The exception always comes back as "401 Authentication required".

Help!