Here is my code for Model Class:

 public class GridModel
    {
        public double ID { get; set; }
        public string SHORT_NAME { get; set; }
        public string CARRIER_NAME { get; set; }
        public List<GridSparklineModel> SellDuration { get; set; }
    }

    public class GridSparklineModel
    {
        public DateTime YMDH { get; set; }
        public double SELL_DURATION { get; set; }
        public string DateString { get { return YMDH.ToString("h tt"); } }
    } 

---------------------------------------

public class GridController : Controller
    {
        //
        // GET: /Grid/

        public ActionResult Index()
        {
            return View();
        }

        public class JsonNetActionResult : ActionResult
        {
            public Object Data { get; private set; }

            public JsonNetActionResult(Object data)
            {
                this.Data = data;
            }

            public override void ExecuteResult(ControllerContext context)
            {
                context.HttpContext.Response.ContentType = "application/json";
                context.HttpContext.Response.Write(JsonConvert.SerializeObject(Data));
            }
        }

        public JsonNetActionResult FetchGraphDataJSON()
        {
            List<GridModel> data = new List<GridModel>();

            //DataFetching Logic
            DataTable dt = FetchFirstDataTable();

            if (dt.Rows.Count != 0)
            {
                foreach (DataRow row in dt.Rows)
                {
                    GridModel model = new GridModel();

                    model.ID = Convert.ToDouble(row["ID"].ToString());
                    model.SHORT_NAME = row["SHORT_NAME"].ToString();
                    model.CARRIER_NAME = row["CARRIER_NAME"].ToString();

                    model.SellDuration = new List<GridSparklineModel>();

                    double carrierId = Convert.ToDouble(row["ID"].ToString());

                    DataTable dt2 = GetDt2();

                    foreach (DataRow item2 in dt2.Select("ID=" + carrierId))
                    {
                        model.SellDuration.Add(new GridSparklineModel { YMDH = DateTime.Parse(item2["YMDH"].ToString()), SELL_DURATION = Convert.ToDouble(item2["SELL_DURATION"]) });
                    }

                    data.Add(model);
                }
            }

            return new JsonNetActionResult(data);
        }

        public DataTable FetchFirstDataTable()
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("ID", typeof(double));
            dt.Columns.Add("SHORT_NAME");
            dt.Columns.Add("CARRIER_NAME");

            dt.Rows.Add(1, "A", "Carrier A");
            dt.Rows.Add(2, "B", "Carrier B");
            dt.Rows.Add(3, "C", "Carrier C");
            dt.Rows.Add(4, "D", "Carrier D");
            dt.Rows.Add(5, "E", "Carrier E");
            dt.Rows.Add(6, "F", "Carrier F");
            dt.Rows.Add(7, "G", "Carrier G");
            return dt;
        }

        public DataTable GetDt2()
        {
            DataTable dt = new DataTable();

            dt.Columns.Add("YMDH");
            dt.Columns.Add("ID", typeof(double));
            dt.Columns.Add("SELL_DURATION");

            dt.Rows.Add("2009-03-07 00:00:00.000", 1, 222.999995);
            dt.Rows.Add("2009-03-07 01:00:00.000", 1, 75.816664);
            dt.Rows.Add("2009-03-07 02:00:00.000", 1, 39.349995);
            dt.Rows.Add("2009-03-07 03:00:00.000", 1, 275.91666);
            dt.Rows.Add("2009-03-07 04:00:00.000", 1, 352.666641);
            dt.Rows.Add("2009-03-07 00:00:00.000", 2, 80.783324);
            dt.Rows.Add("2009-03-07 01:00:00.000", 2, 162.049985);
            dt.Rows.Add("2009-03-07 02:00:00.000", 2, 107.199989);
            dt.Rows.Add("2009-03-07 03:00:00.000", 2, 44.849994);
            dt.Rows.Add("2009-03-07 04:00:00.000", 2, 156.516658);
            dt.Rows.Add("2009-03-07 05:00:00.000", 2, 467.583312);
            dt.Rows.Add("2009-03-07 06:00:00.000", 2, 455.199977);

            return dt;
        }

    }

-----------------------------------------

<!DOCTYPE html>
<html>
<head>
    <title></title>

    <!-- Ignite UI Required Combined CSS Files -->
    <link href="../igniteui/css/themes/infragistics/infragistics.theme.css" rel="stylesheet" />
    <link href="../igniteui/css/structure/infragistics.css" rel="stylesheet" />

    <script src="../js/modernizr.min.js"></script>
    <script src="../js/jquery.min.js"></script>
    <script src="../js/jquery-ui.min.js"></script>

    <!-- Ignite UI Required Combined JavaScript Files -->
    <script src="../igniteui/js/infragistics.core.js"></script>
    <script src="../igniteui/js/infragistics.dv.js"></script>
    <script src="../igniteui/js/infragistics.lob.js"></script>

</head>
<body>

     <!-- Target element for the igGrid -->   
    <table id="grid"></table>
    
    <script>
        $(document).ready(function () {
            var url = '@Url.Action("FetchGraphDataJSON", "Grid")';

            var rawData = null;
            $.ajax({
                // have to use synchronous here, else the function
                // will return before the data is fetched
                async: false,
                url: url,
                dataType: "json",
                success: function (data) {
                    rawData = data;
                }
            });

            var plotData = []

            for (i = 0; i < rawData.length; i++) {               
                plotData.push([rawData[i].ID, rawData[i].SHORT_NAME, rawData[i].CARRIER_NAME], [rawData[i].SellDuration]);
            }


            $(function () {

                $("#grid").igGrid({
                    dataSource: plotData,
                    autoGenerateColumns: false,
                    height: "400px",
                    rowsRendered: function (evt, ui) {
                        //get data collection
                        var dataSource = ui.owner.dataSource;
                        $(".order-sparkline").each(function (i) {
                            $(this).igSparkline({
                                dataSource: dataSource.findRecordByKey(
                                     $(this).data("ID")).SellDuration,
                                height: "24px",
                                width: "100%",
                                valueMemberPath: 'SELL_DURATION'
                            })
                            .css("background-color", "transparent");
                        });
                    },
                    primaryKey: "ID",
                    rowTemplate: "<tr><td></td><td>${ID}</td><td>${SHORT_NAME}</td>" +
                        "<td>${CARRIER_NAME}</td><td><div data-id='${ID}' class='order-sparkline'></div></td></tr>",
                    columns: [
                        { key: "ID", hidden: true },
                        { key: "SHORT_NAME", headerText: "Short Name" },
                        { key: "CARRIER_NAME", headerText: "Name" },                        
                        { key: "SellDuration", headerText: "Duration" }
                    ]
                });

            });
        });

    </script>

</body>
</html>

I can see the Grid with 3 columns and last column for Sparkline is not shown. Can anybody please suggest what should be done to show the sparkline in grid.