Error: ServiceHost only supports class service Types

While adding service reference to a IIS hosted WCF service in Silverlight application, I ran into the following error.

In your WCF service if you look at markup .svc file of your service, you will notice from where reference to ServiceHost came. In my service, it looks like as below.

<%@ ServiceHost Language="C#" Debug="true" 
Service="SearchService.SearchServer" CodeBehind="SearchServer.svc.cs" %>

You can see that there are only 2 things that can go wrong in this declaration. One, the service class that implements your service does not match with the declaration in this mark up. This is usually the cause of this error because most of the time you modify the wizard generated interface and service class names and you forget to modify the declarations in this SVC file. Make sure that all entries in mark up file match with actual class and interface names.