How do I get the CalendarExtender to show Gridview Templete Field

Hi

i want to use Calendar Extender Control in My grid view's temple field how can i use that calendar control

Code (calendar extender is associated with End Date):

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Employee Id,Start Date" DataSourceID="SqlDataSource1">
<Columns>
<asp:CommandField ShowEditButton="True" />
<asp:BoundField DataField="Employee Id" HeaderText="Employee Id" ReadOnly="True" SortExpression="Employee Id" />
<asp:TemplateField HeaderText="Start Date" SortExpression="Start Date">
<EditItemTemplate>
<asp:Label ID="Label1" runat="server" Text='<%# Eval("[Start Date]") %>'></asp:Label>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label1" runat="server" Text='<%# Bind("[Start Date]") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="End Date" SortExpression="End Date">
<EditItemTemplate>
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("[End Date]") %>'></asp:TextBox>
<cc1:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="Textbox1">
</cc1:CalendarExtender>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label2" runat="server" Text='<%# Bind("[End Date]") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>