Accessing Google Spreadsheets with C# using Google Data API fails with Mono

I'm trying to access my Google spreadsheets using the GData API. I have followed the example which looks like:

var service = new SpreadsheetsService("myTest");
service.setUserCredentials(username, password);
var query = new SpreadsheetQuery();
var feed = service.Query(query);

This should return a feed with a list of spreadsheets. However this fails with:

Google.GData.Client.GDataRequestException: Execution of request failed: http://spreadsheets.google.com/feeds/spreadsheets/private/full ---> System.Net.WebException: The remote server returned an error: (404) Not Found.

When I try the above link directly in my browser I'm able to download the feed, as long as I'm logged in into my Google account.

Some further information:

1. I'm not behind a firewall
2. I have checked my username (maurits.rijk at gmail.com) and password several times
3. I am using Mandriva in VirtualBox on a MacBook
4. All my code is compiled with Mono

I tried the same functionality in Java on OS-X. That code runs as expected.