Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object
  at Google.GData.Client.Utilities.UriEncodeReserved (System.String content) [0x00000] 
  at Google.GData.Client.GDataGAuthRequest.QueryAuthToken (Google.GData.Client.GDataCredentials gc) [0x00000] 
  at Google.GData.Client.GDataGAuthRequest.EnsureCredentials () [0x00000] 
  at Google.GData.Client.GDataRequest.EnsureWebRequest () [0x00000] 
  at Google.GData.Client.GDataGAuthRequest.EnsureWebRequest () [0x00000] 
  at Google.GData.Client.GDataRequest.Execute () [0x00000] 
  at Google.GData.Client.GDataGAuthRequest.Execute (Int32 iRetrying) [0x00000]