Fill TextBox on DropDownList change using jQuery Ajax in ASP.Net MVC

I am using below script, when DropDownList value get change, then TextBox value get populate, but it is not populating value in TextBox.

<script type="text/javascript">
   $(document).ready(function() {
       $("#Item").change(function () {
            var itemId= $("#Item").val();
            GetItemUnitPrice(itemId);
        });
   });

    function GetItemUnitPrice(itemId)
    {
        alert(itemId);
        $.ajax({
            async: true,
            type: 'GET',
            dataType: 'JSON',
            contentType: 'application/json; charset=utf-8',
            url:'/Home/getItemUnitPrice', data: {itemId: itemId},
            success: function(data){
                $("#txtUnitPrice").val(parseFloat(data).toFixed(2));
            }, 
            error: function() {
                alert("There is some problem to get the Unit Price.");
            }
        });
    }
</script>

Below is Dropdown and textbox

<fieldset>
    <legend> Restaurat Items:</legend>
    <div class="container">
        <div class="row">
            <div class="col-md-4">
                <div class="form-group" style="background:white;">
                    Item  :
                    @Html.DropDownList("Item", new SelectList(Model.Item2, dataValueField: "value", dataTextField: "Text"), new { @class = "form-control", @id = "select2-3" })
                </div>
            </div>
            <div class="col-md-4">
                <div class="form-group">
                    Untit Price  :
                    <input type="text" style="text-align:right;" readonly="readonly" id="txtUnitPrice" value="0.00" name="UnitPrice" class="form-control" />
                </div>
            </div>
            <div class="col-md-4">
                <div class="form-group">
                    Qunantity  :
                    <input type="text" id="txtQuantity" style="text-align:right;" value="0.00" name="Quantity" class="form-control" />
                </div>
            </div>
            <div class="col-md-4">
                <div class="form-group">
                    Discount  :
                    <input type="text" id="txtDiscount" style="text-align:right;" value="0.00" name="Discount" class="form-control" />
                </div>
            </div>
            <div class="col-md-4">
                <div class="form-group">
                    Total  :
                    <input type="text" readonly="readonly" style="text-align:right;" id="txtTotal" value="0.00" name="Total" class="form-control" />
                </div>
            </div>
            <div class="col-md-4">
                <div class="form-group">
                    <input type="button" value="Add To List" name="AddToList" style="margin-top: 20px" id="btnAddToList" class="btn btn-success" />
                </div>
            </div>
        </div>
    </div>
</fieldset>

Controller

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using WebApplication13.Repositories;
using WebApplication13.Models;

namespace WebApplication13.Controllers
{
    public class HomeController : Controller
    {
        // GET: Home
        private readonly RestaurantDBEntities restaurantDBEntities;
        public HomeController()
        {
            restaurantDBEntities = new RestaurantDBEntities();
        }

        public ActionResult Index()
        {
            CustomerRepositories objCustomerRepository = new CustomerRepositories();
            ItemRepositories objItemRespository = new ItemRepositories();
            PaymentRepositories objPaymentRepository = new PaymentRepositories();

            var objMultipleModels = new Tuple<IEnumerable<SelectListItem>, IEnumerable<SelectListItem>, IEnumerable<SelectListItem>>
                (objCustomerRepository.GetAllCustomer(), objItemRespository.GetallItem(), objPaymentRepository.GetAllPaymentType());
            return View(objMultipleModels);

        }
        [HttpGet]
        public JsonResult getItemUnitPrice(int itemId)
        {
            decimal? UnitPrice = restaurantDBEntities.Items.Single(model => model.ItemId == itemId).ItemPrice;
            return Json(UnitPrice, JsonRequestBehavior.AllowGet);
        }
    }
}