XML Serialized and Deserialized

There is a question,
Class Config
A List of "Samples"
A List of "Methods"
End Class

Each sample has a property "Method", which is reference to one method in List(Of Method)

When I serialized and deserialized Config class, The method in Sample is not in List(Of Method)

Because XML format is easy to save data, but it has this problem, how to workaround?

Thanks.