Could you please give us more details on how you created the service? Did you use the Add OpenAccess Service wizard
or you created it manually?
Please note that you have to specify different Uri template for the methods serializing in JSON as well as set the ResponceFormat parameter of the WebGet attribute to Json. Here is how your method should look like:
, ResponseFormat = WebMessageFormat.Json)]
Please give this a try and let us know if it does not help.
the Telerik team
Telerik OpenAccess ORM Meets ASP.NET Web API. Read more.