Header namespace mismatch in member {1} of type {0}. The header namespace found in the description is {2}. The element namespace ...

Header namespace mismatch in member {1} of type {0}. The header namespace found in the description is {2}. The element namespace deduced by the formatter is {3}. This mismatch can happen if the Namespace specified in XmlElementAttribute or XmlArrayAttribute does not match the namespace specified in the MessageHeaderAttribute or MessageHeaderArrayAttribute or the contract namespace.