vs2008中使用ScriptManager调用该页面的后台c#函数

下面是一个简单的例子

<% @ Page Language = " C# " %>
<% @ Import Namespace = " System.Web.Services " %>
< script runat ="server" >
protected void Page_Load(object sender, EventArgs e)
    {

    }


    [WebMethod]
    public static DateTime GetCurrentTime()
    {        
        return DateTime.Now;    
        
    }

</ script >

<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd" >
< html xmlns ="http://www.w3.org/1999/xhtml" >
< head runat ="server" >
    < title > Untitled Page </ title >
</ head >
< body >
     < form id ="form1" runat ="server" >
         < asp:ScriptManager ID ="ScriptManager1" runat ="server" EnablePageMethods ="true" >
         </ asp:ScriptManager >
     < div >
         < input id ="Button1" type ="button" value ="button" onclick ="showit()" />
     </ div >
    
     < script language ="javascript" type ="text/javascript" >
    function showit()
    {
        PageMethods.GetCurrentTime(suc);
    }
    function suc(result)
    {
        alert(result);
    }
    
     </ script >
     </ form >
</ body >

</ html >