mvc telerik kendo reference error

Hi experts,

I'm working with the Telerik UI for ASP.NET MVC DropDownList control.

I'm recreating this grouping example:

In my example I'm using Visual Studio 2013, MVC 5, C#, Razor, Entity Framework 6 database first.

I get one error in my code but i'm stuck on how to fix this one error.

This is what my application directory looks like.
I'm getting this error on .Group in my view called Index.cshtml as shown in this pic:
error message
These are the the items i'm referencing in my project"
my references
This is my model:
my model

So this is my code:


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace NorthwindApp.Models
    public class CustomerViewModel
        public string CustomerID { get; set; }
        public string CompanyName { get; set; }
        public string ContactName { get; set; }
        public string ContactTitle { get; set; }
        public string Address { get; set; }
        public string City { get; set; }
        public string Region { get; set; }
        public string PostalCode { get; set; }
        public string Country { get; set; }
        public string Phone { get; set; }
        public string Fax { get; set; }
        public Nullable<bool> Bool { get; set; }

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using NorthwindApp.Models;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using Kendo.Mvc.UI;
using Kendo.Mvc.Extensions;

namespace NorthwindApp.Controllers
    public class HomeController : Controller

        // GET: /Home/
        public ActionResult Index()

            return View();

        public ActionResult Customers_Read()
            return Json(GetCustomers(), JsonRequestBehavior.AllowGet);

        private static IEnumerable<CustomerViewModel> GetCustomers()
            var northwind = new NorthwindEntities();
            return northwind.Customers.Select(customer => new CustomerViewModel
                CustomerID = customer.CustomerID,
                CompanyName = customer.CompanyName,
                ContactName = customer.ContactName,
                ContactTitle = customer.ContactTitle,
                Address = customer.Address,
                City = customer.City,
                Region = customer.Region,
                PostalCode = customer.PostalCode,
                Country = customer.Country,
                Phone = customer.Phone,
                Fax = customer.Fax
                //Bool = customer.Bool


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@*@model IEnumerable<northwindapp.models.employee>*@

@using Kendo.Mvc.UI.Fluent.

    <link href="~/Content/kendo.common.min.css" rel="stylesheet" type="text/css" />
    <link href="~/Content/kendo.default.min.css" rel="stylesheet" type="text/css" />

    <script src="~/Scripts/jquery.min.js" type="text/javascript"></script>
    <script src="~/Scripts/kendo.web.min.js" type="text/javascript"></script>
    <script src="~/Scripts/kendo.aspnetmvc.min.js" type="text/javascript"></script>

<div class="demo-section">

          .HtmlAttributes(new { style = "width:250px" })
          .OptionLabel("Select a contact name")
          .DataSource(source => source
              .Group(g => g.Add("Country", typeof(string)))
              .Transport(transport => transport
                .Read(read =>
                    // call the Customers_Read JSON method found in the controllter called HomeController.cs
                    read.Action("Customers_Read", "DropDownList");

    .demo-section {
        width: 250px;
        margin: 35px auto 50px;
        padding: 30px;

        .demo-section h2 {
            text-transform: uppercase;
            font-size: 1.2em;
            margin-bottom: 10px;

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Anyone know why I'm getting this error on my view? How do i fix this error?
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Fareed Ali KhanCommented:
You are getting this error because you are using ReadOnlyCustomDataSourceBuilder.

You should have to use CustomDataSourceBuilder.

Also customers model is not included on the view?

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