Ajax更新面板 - 我錯過了什麼？

Question

問題：當郊區下拉列表值發生變化時 - 頁面將被回傳。

期望的結果：在下拉更改值下拉列表的更新，而不需要頁面後回郵編文本框的值（崗位代碼文本框通常是隱藏的）

頁代碼：背後

<asp:ScriptManager ID="ScriptManager1" runat="server" /> 
      <asp:DropDownList ID="Suburb" runat="server" DataTextField="LocalityPhrase" 
     DataValueField="Locality" AutoPostBack="true" class="DropDown" OnSelectedIndexChanged="Suburb_SelectedIndexChanged"/> 
     <asp:UpdatePanel runat="server" id="UpdatePanelPostCode" UpdateMode="Conditional"> 
     <ContentTemplate> 
     <asp:TextBox ID="Postcode" runat="server" Visible="true"/> 
     </ContentTemplate> 
     <Triggers> 
       <asp:AsyncPostBackTrigger ControlID="Suburb" EventName="SelectedIndexChanged" /> 
      </Triggers> 
     </asp:UpdatePanel> 

代碼：

Protected Sub Suburb_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Suburb.SelectedIndexChanged 
     'get postcode from suburb drop down 
     Dim pCode As String = "" 
     If Suburb.SelectedValue <> "" Then 
      pCode = Suburb.SelectedItem.Text.Substring(Len(Suburb.SelectedItem.Text) - 5, 4) 
     End If 
     Postcode.Text = pCode 
End Sub 

Answer 1

看來我的安裝AJAX工具包出現了問題。在Visual Studio（2008）中刪除並重新加載它，一切都很好。