AppDomain and MarshalByRefObject life time : how to avoid RemotingException?

see answer here:

http://social.msdn.microsoft.com/Forums/en-US/netfxremoting/thread/3ab17b40-546f-4373-8c08-f0f072d818c9/

which basically says:

[SecurityPermissionAttribute(SecurityAction.Demand, Flags = SecurityPermissionFlag.Infrastructure)]
public override object InitializeLifetimeService()
{
  return null;
}