Working with Remote Validation asp.net MVC

i like to try using remote validation that i spot on this link: http://www.youtube.com/watch?v=Ll8VtDRj8L4

i've followed the instruction and it worked but the problem is, when i try to add data from referenced table, the validation wont worked

Model Class:

public partial class ms_student
{
    public int ID { get; set; }
    public string student_code{ get; set; }
    public virtual ms_person ms_person { get; set; }
}

public partial class ms_person
{
    public string name{ get; set; }
    public string email { get; set; }
    public virtual ms_student ms_student { get; set; }
}

Metadata:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Web.Mvc;

namespace Test.Models
{
    [MetadataType(typeof(personMD))]
    public partial class ms_person
    {
    }

    public class personMD
    {
        [Required(ErrorMessage = "Email is required")]
        [EmailAddress(ErrorMessage = "Invalid Email Address")]
        [Remote("CheckEmailExist", "Administrator", ErrorMessage = "Email Already Exist")]
        public object email { get; set; }

    }
}

Controller:

public JsonResult CheckEmailExist(string email) // the error i think from email paramater, cause the video said to make the paramater exactly the same name...
{
    return Json(!db.ms_person.Any(m => m.email == email), JsonRequestBehavior.AllowGet);
}

Views:

@model Test.Models.ms_student

@using (Html.BeginForm("CreateStudent", "Administrator", FormMethod.Post,
                        new { enctype = "multipart/form-data" }))
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true)

    @Html.TextBoxFor(model => model.student_code) //this one work and already tested
    @Html.ValidationMessageFor(model => model.student_code)

    @Html.TextBoxFor(model => model.ms_person.email) //if you inspect element on browser the NAME are ms_person.email and ID are ms_person_email
    @Html.ValidationMessageFor(model => model.ms_person.email)
}

i've tried to change the JsonResult Controller paramater into (string ms_person.email), but there error said namespace email could not be found.. also tried to use (string ms_person_email), won't work either

i've also tested using student_code, the student_code field work properly because the student_code attribute are in the same Model(ms_student), not like email(reference to ms_person)

All metadata validation work, like required on both Model, so i'm guessing the error is on the JsonResult parameter

Thank you very much