Header namespace mismatch in operation {0} from contract {1}:{2}. The header namespace found in the description is {3}. The ...

Header namespace mismatch in operation {0} from contract {1}:{2}. The header namespace found in the description is {3}. The element namespace deduced by the formatter is {4}. 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.