Hébergement d'un service WCF dans un numéro de site Web: System.ArgumentException: ServiceHost uniquement prend en charge les types de service de classe

J'ai quelque chose comme ça:

MathServicelibrary STRT> (Bibliothèque de services WCF) P>

    <system.serviceModel>
        <services>
            <service behaviorConfiguration="defaultServiceBehavior" name="MathServiceLibrary.MathService">
                <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
                <endpoint address="" binding="wsHttpBinding" contract="MathServiceLibrary.IMathService">
                    <identity>
                        <dns value="localhost"/>
                    </identity>
                </endpoint>
            </service>
        </services>
        <behaviors>
            <serviceBehaviors>
                <behavior name="defaultServiceBehavior">
                    <serviceMetadata httpGetEnabled="true"/>
                    <serviceDebug includeExceptionDetailInFaults="false"/>
                </behavior>
            </serviceBehaviors>
        </behaviors>
        <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
    </system.serviceModel>