Session state server saying extended class no serializable

[firedog]

I am storing an object in session state (using local session state server), class def is:\[code\] [Serializable] public class ExtendedOAuth2Parameters : OAuth2Parameters\[/code\]but the service is still reporting:\[code\]Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted.[SerializationException: Type 'Google.GData.Client.OAuth2Parameters' in Assembly 'Google.GData.Client, Version=2.1.0.0, Culture=neutral, PublicKeyToken=04a59ca9b0273830' is not marked as serializable.]\[/code\]How to get around it?