Unsupported media type requested when requesting application/json on WCF Data Service

I am building a WCF data service (with .net 4.5 VS 2012) using Reflection Provider (http://msdn.microsoft.com/en-us/library/dd728281.aspx) on my existing classes. I can successfully access the service with "Accept: application/atom+xml" in request header. however, I got an error "Unsupported media type requested" when changing "Accept" to "application/json" in request header. As I learned, WCF data service supports JSON, what should I do to enable querying json data on the service? Thanks Edit: I paste my code below: first I have the Product class defined: ``` [DataServiceKeyAttribute("Id")] public class Product { public int Id { get; set; } public int Price { get; set; } public string Name { get; set; } } ``` then I have my ProductContext class defined: ``` public class ProductContext { private List<Product> products = new List<Product>(); public ProductContext() { for (int i = 0; i < 100; i++) { var product = new Product(); product.Id = i; product.Name = "ID - " + i.ToString(); product.Price = i + 100; products.Add(product); } } public IQueryable<Product> Products { get { return products.AsQueryable(); } } } ``` and my ProductService.svc.cs ``` [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class ProductsService : DataService<ProductContext> { // This method is called only once to initialize service-wide policies. public static void InitializeService(DataServiceConfiguration config) { // TODO: set rules to indicate which entity sets and service operations are visible, updatable, etc. // Examples: config.SetEntitySetAccessRule("Products", EntitySetRights.AllRead); //config.SetServiceOperationAccessRule("MyServiceOperation", ServiceOperationRights.All); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V3; } } ```