How to pass a json array of type object to MVC controller class

I'm trying to pass through a JSON array through to my controller. I want to be able to post data to the database from a JSON array which is populated and passed to the controller through javascript in the client side. However, it is not receiving anything in the controller. My controller received a null value as the parameter.

The following is my controller:

  [HttpPost]
    [SiteAuthorize]
    public ActionResult SaveDashboard(List<Dashboard> dashboards)
    {
        try
        {

            string result = "";
            return Json(new { Result = result, Message = "" }, JsonRequestBehavior.AllowGet);
        }
        catch (Exception ex)
        {
            return Json(new { Result = "Error", Message = ex.Message }, JsonRequestBehavior.AllowGet);
        }
    }

The following is my javascript:

    var dashboards = {
    "DashboardName": '',
    "Width": '',
    "Height": '',
       "DashboardCell": [
           {
               "DashCellId": '',
               "x": '',
               "y": '',
               "DashWidth": '',
               "DashHeight": '',
               "colspan": '',
               "rowspan": '',
               "Active": '',
               "CellValue": '',
               "cellClass": '',
               "previousElementSibling": ''
           }
        ]
    };

    var tablestructure = $("#TableStructure").val();
    var savename = document.getElementById("namedash").value;

    var table = document.getElementById("table");
    var width = table.clientWidth;
    var height = table.clientHeight;
    var DashboardCell = [];
    dashboards.DashboardName = savename;
    dashboards.Width = width;
    dashboards.Height = height;
    for (var i = 0, row; row = table.rows[i]; i++)
    {

        //iterate through rows
        //rows would be accessed using the "row" variable assigned in the for loop
        for (var j = 0, col; col = row.cells[j]; j++)
        {
            for (var x = 0; x < col.attributes.length; x++)
            {
                if (col.attributes[x].localName == "colspan") {
                    var colspan = col.attributes[x].value;
                }
                else if (col.attributes[x].localName == "rowspan") {
                    var rowspan = col.attributes[x].value;
                }
                else if (col.attributes[x].localName == "class")
                {
                    var cellClass = col.attributes[x].value;
                }
            }

            var res = col.id.split(", ");
            var x = parseInt(res[0]);
            var y = parseInt(res[1]);
            var DashHeight = col.clientHeight;
            var DashWidth = col.clientWidth;
            if (j > 0) {
                var previousElementSibling = col.previousElementSibling.id;
            }
            else {
                var previousElementSibling = '';
            }
            var DashCellID = col.id;
            var CellValue = col.innerText;
            var DashCell = { DashCellId: DashCellID, x: x, y: y, DashWidth: DashWidth, DashHeight: DashHeight, colspan: colspan, rowspan: rowspan, Active: 1, CellValue: CellValue, cellClass: cellClass, previousElementSibling: previousElementSibling };
            DashboardCell.push(DashCell);

            //iterate through columns
            //columns would be accessed using the "col" variable assigned in the for loop
        }
    }
    dashboards.DashboardCell = DashboardCell;

    $.ajax({
        url: '/KPIReportAdmin/SaveDashboard',
        type: "POST",
        dataType: "json",
        contentType: "application/json",
        data: { dashboards: JSON.stringify(dashboards) },
        success: function (result)
        {

        },
        error: function (result) {
            alert("Failed");
        }

    });

The following is my class:

public class DashboardCell
{
    public int Width { get; set; }
    public int Height { get; set; }
    public bool Active { get; set; }
    public int colspan { get; set; }
    public int rowspan { get; set; }
    public int x { get; set; }
    public int y { get; set; }
    public string CellValue { get; set; }
    public string DashCellId { get; set; }
    public string cellClass { get; set; }
    public int previousElementSibling { get; set; }
}

public class Dashboard
{
    public string Name { get; set; }
    public int Height { get; set; }
    public int Width { get; set; }
    public int UserID { get; set; }
    public List<DashboardCell> DashboardCell { get; set; }
}

I expect to receive the dashboard list in SaveDashboard but I'm getting null