System.linq.dynamic.parseexception: 'expression expected'

//  This throws at here on this line. System.Linq.Dyanmic.ExpressionParse.ParsePrimaryStart();

<pre>
       [HttpPost]
       public ActionResult GetList()
        {
            //Server side Parameter.
            int start = Convert.ToInt32(Request["start"]);
            int length = Convert.ToInt32(Request["length"]);
            string searchValue = Request["search[value]"];
            string sortColumnName = Request["columns[" + Request["order[0][column]"] + "][name]"];
            string sortDirection = Request["order[0] [dir]"];

            List<TblEventsManagements> empList = new List<TblEventsManagements>();
            using (eNtsaOnlineRegistrationDBContext db = new eNtsaOnlineRegistrationDBContext())
            {
                 empList = db.TblEventsManagements.ToList<TblEventsManagements>();
                int totalrows = empList.Count;

                if (!string.IsNullOrEmpty(searchValue))
                {
                    empList = empList.Where(x => x.TrainingType.ToLower().Contains(searchValue.ToLower()) || x.TrainingDescription.ToLower().Contains(searchValue.ToLower()) || x.Price.ToString().Contains(searchValue.ToLower())
                    || x.Venue.ToLower().Contains(searchValue.ToLower()) || x.Facilitator.ToLower().Contains(searchValue.ToLower()) || x.WhoAttend.ToLower().Contains(searchValue.ToLower()) || x.Rsvp.ToLower().Contains(searchValue.ToLower())).ToList<TblEventsManagements>();


                }
                    int totalrowsafterfiltering = empList.Count;

                    empList = empList.OrderBy(sortColumnName + " " + sortDirection).ToList<TblEventsManagements>(); // This line thrown the above error

                    empList = empList.Skip(start).Take(length).ToList<TblEventsManagements>();

                    
                
                return Json(new { data = empList, draw = Request["draw"], recordsTotal = totalrows, recordsFiltered = totalrowsafterfiltering }, JsonRequestBehavior.AllowGet);
            }


                
        }

<script>

      $(document).ready(function () {

             $("#EventManagementTable").DataTable({
              "ajax": {
                  "url": "/Dashboard/GetList",
                  "type": "POST",
                  "datatype":"json"
              },
                 "columns": [
                  {"data": "TrainingType", "name": "TrainingType"},
                  { "data": "TrainingDescription", "name": "TrainingDescription" },
                  { "data": "Price", "name": "Price" },
                  { "data": "Venue", "name": "Venue" },
                  { "data": "Facilitator", "name": "Facilitator" },
                  { "data": "WhoAttend", "name": "WhoAttend" },
                  {"data": "RSVP", "name": "RSVP"},
              ],

              "serverSide": "true",
              "order":[0,"asc"],
              "processing": "true",
              "language": {
                  "processing":"processing... please wait"
              }



          });

      });