我的asp .net项目里面有个aspx文件，想增加个ajax日历控件，可是增加后不显示！这是它的源描述，请ajax大侠帮忙看看

<%@ Page language="c#" Codebehind="Add.aspx.cs" AutoEventWireup="false" Inherits="IFMIS.Equipment.FixTaskManage.FixTask.Add" %>

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>

<%@ Register Assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
 Namespace="System.Web.UI" TagPrefix="asp" %>
<HTML>
<HEAD runat="server" >
<title>Add</title>
<LINK href="../../../css/a.css" rel="stylesheet">
</HEAD>
<body bgColor="#ccff99">
<form id="Form1" method="post" runat="server">
 <asp:ScriptManager ID="ScriptManager1" EnableScriptGlobalization="true"
 EnableScriptLocalization="true" runat="server">
 </asp:ScriptManager>

<TABLE id="Table2" style="BORDER-RIGHT: #cccccc 1px; BORDER-TOP: #cccccc 1px; BORDER-LEFT: #cccccc 1px; BORDER-BOTTOM: #cccccc 1px; BORDER-COLLAPSE: collapse; BACKGROUND-COLOR: white"
borderColor="#cccccc" height="472" cellSpacing="0" cellPadding="2" rules="all" bgColor="#ffffcc"
border="1" width="100%">
<TR>
<TD bgColor="#669966" colSpan="4" height="48">
<IMG height="16" hspace="3" src="\img\loca.gif" width="16" align="absMiddle">位置: 装备维修
> 修理工程管理 > 等级修理工程基本信息添加
<asp:label id="lblID" runat="server" Visible="False">0</asp:label>
</TD>
</TR>
<TR>
<TD width="100%" bgColor="#ffffcc" colSpan="4" height="357">
<asp:panel id="Panel1" runat="server" Width="100%" Height="357px" BackColor="WhiteSmoke" BorderStyle="Inset"
BorderColor="#400000" BorderWidth="2px">

<TABLE id="Table1" height="341" cellSpacing="1" cellPadding="1" border="1" width="100%">
<TBODY>
<TR>
<TD width="20%" colSpan="4" height="37">
<asp:label id="Label1" runat="server" Width="192px" Height="12px" Font-Names="幼圆" Font-Bold="True"
Font-Size="Small">等级修理工程基本信息：</asp:label></TD>
</TR>
<TR style="font-size: 10pt">
<TD width="20%" height="35">
工程代号
</TD>
<TD width="30%" height="35"><asp:textbox id="tboxTaskName" runat="server" Width="168px"></asp:textbox><asp:requiredfieldvalidator id="RequiredFieldValidator2" runat="server" ErrorMessage="必填" ControlToValidate="tboxTaskName"></asp:requiredfieldvalidator></TD>
<TD width="20%" height="35" style="font-size: 10pt; color: #222222; font-family: 幼圆">
修理等级
</TD>
<TD height="35" width="30%"><asp:dropdownlist id="DDLTaskGrade" runat="server" Width="152px"></asp:dropdownlist></TD>
</TR>
<TR>
<TD width="20%" height="35">
需求单位
</TD>
<TD width="30%" height="35"><asp:dropdownlist id="DDLRequireCompany" runat="server" Width="168px"></asp:dropdownlist></TD>
<TD width="20%" height="35">舷号</TD>
<TD height="35" width="30%"><asp:textbox id="tboxXuanhao" runat="server" Width="152px"></asp:textbox><asp:requiredfieldvalidator id="RequiredFieldValidator1" runat="server" ErrorMessage="必填" ControlToValidate="tboxXuanhao"></asp:requiredfieldvalidator></TD>
</TR>
<TR>
<TD width="20%" height="38">
负责部门
</TD>
<TD width="30%" height="38"><asp:dropdownlist id="DDLDepartID" runat="server" Width="168px" AutoPostBack="True"></asp:dropdownlist></TD>
<TD width="20%" height="38">
负责人
</TD>
<TD height="38" width="30%"><asp:dropdownlist id="DDLTaskOnDutyPerson" runat="server" Width="152px"></asp:dropdownlist></TD>
</TR>
<TR>
<TD width="20%" height="35">
任务下达时间

</TD>
<TD width="30%" height="35"><asp:textbox id="tboxTaskSendTime" runat="server" Width="168px"></asp:textbox> 
 <ajaxToolkit:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="tboxTaskSendTime">
 </ajaxToolkit:CalendarExtender>
 <IMG height="16" hspace="3" src="\img\loca.gif" width="16" align="absMiddle"></TD>
<TD width="20%" height="35">任务开始时间</TD>
<TD height="35" width="30%">
<asp:textbox id="tboxTaskBeginTime" runat="server" Width="152px"></asp:textbox>
<asp:regularexpressionvalidator id="RegularExpressionValidator2" runat="server" ErrorMessage="20051010" ControlToValidate="tboxTaskBeginTime"
Width="48px" ValidationExpression="^200+[5678]+[01]+[0123456789]+[0123]+[0123456789]$"></asp:regularexpressionvalidator></TD>
</TR>
<TR>
<TD width="20%" height="36">任务结束时间</TD>
<TD width="30%" height="36">
<asp:textbox id="tboxTaskEndTime" runat="server" Width="168px"></asp:textbox>
<asp:regularexpressionvalidator id="RegularExpressionValidator3" runat="server" ErrorMessage="20051010" ControlToValidate="tboxTaskEndTime"
ValidationExpression="^200+[5678]+[01]+[0123456789]+[0123]+[0123456789]$"></asp:regularexpressionvalidator></TD>
<TD width="20%" height="36">备注</TD>
<TD height="36" width="30%">
<asp:textbox id="tboxDes" runat="server" TextMode="MultiLine" Height="115px" Width="234px"></asp:textbox></TD>
</TR>
</TABLE></asp:panel>

<TR>
<TD width="126" bgColor="#ffffcc" height="48"></TD>
<TD width="92" bgColor="#ffffcc" height="48"></TD>
<TD width="272" bgColor="#ffffcc" height="48">


<asp:button id="btnAdd" runat="server" Width="84px" BackColor="#C0C000" Text="添加" Height="30px"></asp:button>


</TD>
<TD bgColor="#ffffcc" height="48"></TD>
</TR>
</TABLE>



<asp:textbox id="tboxDelay" runat="server" Visible="False" Width="48px">0</asp:textbox><asp:dropdownlist id="DDLStopPosition" runat="server" Visible="False" Width="56px"></asp:dropdownlist><asp:dropdownlist id="DDLTaskAddress" runat="server" Visible="False" Width="56px"></asp:dropdownlist><asp:textbox id="tboxTaskContext" runat="server" Visible="False" Width="48px"></asp:textbox></form>
</body>
</HTML>

补充：.NET技术 ,  ASP.NET