从 button列表中获得 commandrgument值

<asp:DataList ID="dlTodos" runat="server" RepeatDirection="Horizontal" Visible="false">
                        <ItemTemplate>
                            <div style="min- 100px">
                                <div class="Transformation_left">
                                </div>
                                <div class="Transformation_middle">
                                    <asp:LinkButton ID="lnkTodo" runat="server" Text=' <%# Container.DataItem %> ' CommandArgument=' <%# Container.DataItem %> '
                                        OnClick="lnkTodo_Click " />
                                </div>
                                <div class="Transformation_right">
                                </div>
                            </div>
                            <div class="Clear">
                            </div>
                        </ItemTemplate>
                        <SeparatorTemplate>
                            <div style=" 50px;">
                            </div>
                        </SeparatorTemplate>
                    </asp:DataList>

 protected void lnkTodo_Click(object sender, EventArgs e)
    {
        //触发事件的Button 
        LinkButton btn = (LinkButton)sender;

        string cmd = btn.CommandArgument;