AjaxPro总是返回null值的问题

[mzx87]

问题如题
后台部分
[AjaxPro.AjaxMethod]
public int VoteHandle(int selectvalue)
{
string userip = Request.UserHostAddress.ToString();
HttpCookie oldcookie = Request.Cookies["UserIP"];
if (oldcookie == null)
{
string sql = "update OptionsT set VoteNum=VoteNum+1 where ID=" + selectvalue;
db.ExecuteQuery(sql);
HttpCookie newcookie = new HttpCookie("UserIP");
newcookie.Expires = DateTime.MaxValue;
newcookie.Values.Add("UserIP", userip);
Response.AppendCookie(newcookie);
return 1;//投票成功
}
else
{
if (userip.Equals(oldcookie["UserIP"].ToString()))
{
return 0;//不能重复投票
}
else
{
string sql = "update OptionsT set VoteNum=VoteNum+1 where ID=" + Convert.ToInt32(selectvalue);
db.ExecuteQuery(sql);
HttpCookie newcookie = new HttpCookie("UserIP");
newcookie.Expires = DateTime.MaxValue;
newcookie.Values.Add("UserIP", userip);
Response.AppendCookie(newcookie);
return 1;//投票成功
}
}
}
JS：
function callback(result)
{
alert('执行到回调函数了');
alert(result);
alert(result.value);
if(result.value==0)
{
alert("对不起，不能重复投票!");
}
else if(result.value==1)
{
alert('投票成功，多谢您的参与！');
}
}

function Vote()
{
if(GetRadioButtonListSelectValue())
{
_Default.VoteHandle(selectvalue,callback);
alert('执行判断了');
}
}
现在的问题是总是返回null值 请各位高手帮忙看下。

[lem12]

HttpContext.Current.Request.UserHostAddress.ToString();
要加上HttpContext.Current