GridView, SortedAscendingCellStyle server side databinding

See more:

ASP.NET

Hi,
I try to use SortedAscendingCellStyle to assign the style of my gridView this is my ASP Code:

<asp:GridView ID="GridView1" runat="server" AllowSorting="True" CellPadding="4" OnSorting="GridView1_Sorting" AutoGenerateColumns="false">
            <SortedAscendingCellStyle CssClass="SortedAscendingCellStyle" />
            <SortedAscendingHeaderStyle CssClass="SortedAscendingHeaderStyle" />
            <SortedDescendingCellStyle CssClass="SortedDescendingCellStyle" />
            <SortedDescendingHeaderStyle CssClass="SortedDescendingHeaderStyle " />
            <Columns>
                <asp:BoundField DataField="Nom" HeaderText="Nom" SortExpression="NOM">
                    <ItemStyle Width="150px" />
                </asp:BoundField>
                <asp:BoundField DataField="Prenom" HeaderText="Prenom">
                    <ItemStyle Width="150px" />
                </asp:BoundField>
                <asp:BoundField DataField="Pseudo" HeaderText="Pseudo"></asp:BoundField>

                <asp:BoundField DataField="Mail" HeaderText="Mail">
                    <ItemStyle Width="140px" />
                </asp:BoundField>
            </Columns>
        </asp:GridView>

there is no problem when i use DataSourceID, but when I use server side databining the SortedAscendingCellStyle Did Not work, this my code behind:

protected void Page_Load(object sender, EventArgs e)
       {
           if (!IsPostBack)
           {
               EmployeDAL oem = new EmployeDAL();
               this.GridView1.DataSource = oem.GetAll();
               GridView1.DataBind();

           }
       }