C#创建控件时出错,NavMenu未知的服务器标记“NavMenu:NavMenu”,求具体怎么写代码,感谢
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="2.aspx.cs" Inherits="_2" %>
<%@ Register Assembly="NavMenu" Namespace="HeroBeastControls.NavMenu" TagPrefix="NavMenu" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
............
<NavMenu:NavMenu ID="NavMenu1" runat="server" >
<NavMenu:NavMenuItem Text="订单管理" CssClass="sys">
<NavMenu:NavMenuSubItem Text="生成订单" Title="生成订单" NavigationURL="#" />
<NavMenu:NavMenuSubItem Text="订单列表" Title="订单列表" NavigationURL="#" />
<NavMenu:NavMenuSubItem Text="合并支付列表" Title="合并支付列表" NavigationURL="#" />
<NavMenu:NavMenuSubItem Text="购房信息" Title="购房信息" NavigationURL="#" />
</NavMenu:NavMenuItem>
</NavMenu:NavMenu>