为什么我的模式的对话框不能覆盖后面的控件

Question

我是在IE8里跑的，说白了就是没有图层
我的代码
<cc1:ModalPopupExtender ID="ModalPopupExtender1" runat="server"
          TargetControlID="Button3"
           PopupControlID="Panel1"
           DropShadow="true"
          Drag="false"  
        RepositionMode="None">
        </cc1:ModalPopupExtender>
        <asp:Button ID="Button3" runat="server"  Text="Button" />
        <asp:Button ID="Button4" runat="server"  Text="Button" OnClick="Button4_Click" />
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:Panel ID="Panel1" runat="server"  BackColor="Lavender">
            <asp:Label ID="Label1" runat="server" Text="用户名"></asp:Label>
            <asp:TextBox ID="txtLoginId" runat="server"></asp:TextBox>
            <br />
            <asp:Label ID="Label2" runat="server" Text="密码"></asp:Label>
            <asp:TextBox ID="txtLoginPwd" runat="server"></asp:TextBox>
            <br />
            <asp:Button ID="Button1" runat="server" Text="登录" />
            <asp:Button ID="Button2" runat="server" Text="注册" /></asp:Panel>
我帮解决下

Answer 1

ModalPopupExtender控件 这个不是asp。net的模式对话框吗