c# - 更新面板总是发布整个页面

Question

问题，我没有获得部分页面发布页面，而是获得整页重新加载，然后在按钮单击时获得表内的下 4 行。知道为什么我没有获得 Ajax 功能。

我在内容页面工作。

<div>
          <asp:ScriptManager ID="ScriptManager1" runat="server">
          </asp:ScriptManager>
           <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" >
          <ContentTemplate>
          <table width="100%" border="0" cellspacing="0" cellpadding="0">
          <tr>
            <th width="35%">Last Degree</th>
            <th width="35%">Institute</th>
            <th width="20%">Year</th>
            <th width="30%">Majors</th>
          </tr>
          <tr id="rowFields">
            <td>
                <asp:TextBox runat="server" ID="txtDegree" type="text" onblur="if(this.value=='' || this.value==null) this.value=''" 
                onfocus="if(this.value==''){this.value='';}" placeholder="Last Degree*" size="35" />
            </td>
            <td>
                <asp:TextBox runat="server" ID="txtInstitue" type="text" onblur="if(this.value=='' || this.value==null) this.value=''" 
                onfocus="if(this.value==''){this.value='';}" placeholder="Institute*" size="35" />
            </td>
            <td>
                <asp:TextBox runat="server" ID="txtYear"  onblur="if(this.value=='' || this.value==null) this.value=''" 
                onfocus="if(this.value==''){this.value='';}" Placeholder="Year*" size="12" />
            </td>
             <td>
                <asp:TextBox runat="server" ID="txtSubjects"  onblur="if(this.value=='' || this.value==null) this.value=''" 
                onfocus="if(this.value==''){this.value='';}" placeholder="Subjects*" size="35" />
            </td>                
          </tr>            
            <tr>          
            <td>
            <asp:PlaceHolder ID="PlaceHolderEdu" runat="server"></asp:PlaceHolder>
            </td>
            <td>
            <asp:PlaceHolder ID="PlaceHolderEdu2" runat="server"></asp:PlaceHolder>
            </td>
            <td>
             <asp:PlaceHolder ID="PlaceHolderEdu3" runat="server"></asp:PlaceHolder>
            </td>
            <td>
                <asp:PlaceHolder ID="PlaceholderEdu4" runat="server"></asp:PlaceHolder>
            </td>         
          </tr>   
          </table>                                    
          </ContentTemplate>

              <Triggers>
                  <asp:AsyncPostBackTrigger ControlID="addmoreEdu" EventName="Click" />
              </Triggers>

          </asp:UpdatePanel>             

             <asp:LinkButton ID="addmoreEdu" runat="server" CssClass="linkbutton" 
                  onclick="addmoreEdu_Click" CausesValidation="False">Add More</asp:LinkButton>  
          </div>