updatapanel怎么设置都不对^^
代码如下，讲PostBackTrigger设为AsyncPostBackTrigger页面没刷新了，但DropDownlist的选择回发不了服务器
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
                    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                        <ContentTemplate>
                            <asp:Label ID="Label4" runat="server" Text="姓名首字母：" Font-Size="20px" ForeColor="White"></asp:Label>
                            <asp:DropDownList ID="DrDList2" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DrDList2_SelectedIndexChanged" Font-Size="20px" Height="24px" Width="70px" style="text-align: right" CssClass="auto-style8">
                                <asp:ListItem>A</asp:ListItem>
                                <asp:ListItem>H</asp:ListItem>
                                <asp:ListItem>Y</asp:ListItem>
                            </asp:DropDownList>
                        </ContentTemplate>
                        <Triggers>
                             <asp:PostBackTrigger  ControlID="DrDList2"  />
                       </Triggers>
                    </asp:UpdatePanel>
------解决方案--------------------
以前贴过一个demo你可以参考一下。