private void OnSorting(int Pageindex)
    {
        try
        {


            if (Session["Sort"] != null)
            {
                GridViewSortExpression = Session["Sort"].ToString();

                //int PageIndex = gvExisting.PageIndex;
                DataSet dsSort = new DataSet();
                DataTable dtSort = new DataTable();
                dsSort = (DataSet)Session["ERecords"];
                dtSort = dsSort.Tables[0];
                // gvExisting.DataSource = SortDataTable(dtSort, false);

                if (dtSort != null)
                {
                    DataView dataView = new DataView(dtSort);

                    if (GridViewSortExpression != string.Empty)
                    {




                        dataView.Sort = string.Format("{0} {1}", GridViewSortExpression, GridViewSortDirection);
                        gvElectronic.DataSource = dataView;

                    }

                }

                gvElectronic.DataBind();
                gvElectronic.PageIndex = Pageindex;
            }
        }
       
        }

    }