DataContractSerializer config section under System.Runtime.Serialization section group could not be loaded

DataContractSerializer config section under System.Runtime.Serialization section group could not be loaded. Verify that machi开发者_开发知识库ne.config is correctly set up.

Do I need to reinstall something?

Data contract serializer goes under behaviour or servicebehaviour http://msdn.microsoft.com/es-es/library/ms731809.aspx