Add shoring in gridview

//Sorting enable and generate event
<asp:GridView runat="server" ID="grvPaymentsList" EnableViewState="true" AutoGenerateColumns="false" OnSorting="grvAcceptDDPaymentsList_Sorting" AllowSorting="true" ShowFooter="true" OnRowDataBound="grvAcceptDDPaymentsList_RowDataBound">


//Define Column
<asp:TemplateField HeaderText="Payment Date" SortExpression="ApplicationDate">
                    <ItemTemplate>
                        <asp:Label Text='<%# Eval("ApplicationDate") %>' ID="lblApplicationDate" runat="server"></asp:Label>
                    </ItemTemplate>

                </asp:TemplateField>

//OnPageLoad
 //Fill ViewState
ViewState["dt"] = dt;


 protected void grvAcceptDDPaymentsList_Sorting(object sender, GridViewSortEventArgs e)
    {
        try
        {
            SetSortDirection(SortDireaction);
            DataTable dataTable = (DataTable)ViewState["dt"];
            if (dataTable != null)
            {
                //Sort the data.
                dataTable.DefaultView.Sort = e.SortExpression + " " + _sortDirection;
                grvAcceptDDPaymentsList.DataSource = dataTable;
                grvAcceptDDPaymentsList.DataBind();
                SortDireaction = _sortDirection;
            }
        }
        catch (Exception ex)
        {
            ShowMessage(ex.Message, "E");
        }
    }

    private void SetSortDirection(object SortDireaction)
    {
        if (sortDirection == "ASC")
        {
            _sortDirection = "DESC";
        }
        else
        {
            _sortDirection = "ASC";
        }
    }
    public string _sortDirection { get; set; }

    public string sortDirection { get; set; }

    public string SortDireaction { get; set; }