webform的验证控件的EnableClientScript设为true为什么还是无法启动客户端脚本验证？
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Login.aspx.cs" Inherits="App003_EmptyWebForm.Login" %>
<!DOCTYPE html>
<asp:Label ID="Label1" runat="server" Text="用户名"></asp:Label>
<asp:TextBox ID="txt_username" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="validate1" runat="server" ControlToValidate="txt_username" ErrorMessage="必填" ValidateRequestMode="Enabled"></asp:RequiredFieldValidator>
<br />
<asp:Label ID="Label2" runat="server" Text="密码"></asp:Label>
<asp:TextBox ID="txt_pwd" runat="server" TextMode="Password"></asp:TextBox>
<asp:RequiredFieldValidator ID="validate2" runat="server" ControlToValidate="txt_pwd" ErrorMessage="必填" ValidateRequestMode="Enabled"></asp:RequiredFieldValidator>
<br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" ValidateRequestMode="Enabled" />
</div>
</form>
上面是代码，哪里有问题？？？
