关于界面局部刷新问题

Question

各位帮忙看看,为什么不能实现局部刷新
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<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true"></asp:ScriptManager>
<asp:Button ID="btnAddKaoqin" runat="server" CssClass="button" Text="增加" onclick="btnAddKaoqin_Click" />
<br />
<asp:UpdatePanel ID="UpdatePanel1" runat="server" >
    <ContentTemplate> 
         <asp:GridView ID="grdKQ" runat="server" AutoGenerateColumns="False" onrowdatabound="grdKQ_RowDataBound" DataKeyNames="AttendanceID">
          <Columns>
          <asp:TemplateField HeaderText="日期">
              <ItemTemplate>
              <asp:TextBox runat="server" ID="txtKQDate" Text='<%#Eval("AttendanceTime")%>' MaxLength="10"></asp:TextBox><button type="button" style="border-width: 0; vertical-align: top; background-color: Transparent;font-size: 8pt;" id="Button1" onclick="javascript:showCalendarControl(this.previousSibling);return false;">
               <img src="../images/minical.gif" /></button>
               <asp:CompareValidator ID="CompareValidator2" Type="Date"  ControlToValidate="txtKQDate" Operator="DataTypeCheck" Display="Dynamic" runat="server" ErrorMessage="格式错误"></asp:CompareValidator>
              </ItemTemplate>
          </asp:TemplateField>
        </asp:GridView>
    </ContentTemplate> 
    <Triggers> 
       <asp:AsyncPostBackTrigger ControlID="btnAddKaoqin" EventName="Click" /> </Triggers> 
</asp:UpdatePanel>