模型状态.MVC 4实体框架

嗨，我有点新的MVC和实体框架，所以我不知道如何解决这个问题。我(相信我)搜索了一个答案，但没有结果。我试图登录我的项目使用实体框架。问题是我加了:

public string Confirmar_contraseña { get; set; }

到"Users"模型来验证密码是否相等(当您在注册屏幕时)

模型:

namespace MundialDeFutbol.Models
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel.DataAnnotations;
    using DataAnnotationsExtensions;
    using System.ComponentModel.DataAnnotations.Schema;
public partial class Usuarios
{
    public int Id { get; set; }
    [Required(ErrorMessage = "El nick (nombre de usuario) es obligatoio")]
    [StringLength(15, MinimumLength = 3, ErrorMessage = "El nombre de usuario debe contener entre 3 y 15 caracteres")]
    public string Nick { get; set; }
    [Required(ErrorMessage = "La contraseña es obligatoria")]
    [StringLength(10, MinimumLength = 4, ErrorMessage = "La contraseña debe contener entre 4 y 10 caracteres")]
    public string Contraseña { get; set; }
    [NotMapped]
    [Compare("Contraseña", ErrorMessage = "Las contraseñas no coinciden")]
    public string Confirmar_contraseña { get; set; }
    public int Tipo_de_usuario { get; set; }
    }
}

视图:

@using MundialDeFutbol.Models
@using System.Web.Optimization
@model Usuarios
@{
    ViewBag.Title = "Login";
}
<h2>Login</h2>
@using (Html.BeginForm("Login", "Usuarios", FormMethod.Post, new { @class = "form-horizontal", @style = "margin-top: 20px;" }))
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true)
    <div class="form-group">
        <label for="Nick" class="col-sm-2 control-label">@Html.LabelFor(model => model.Nick)</label>
        <div class="col-sm-10">
            @Html.TextBoxFor(model => model.Nick, new { @class = "form-control", @placeholder = "Nombre de usuario" })
            <strong>
                @Html.ValidationMessageFor(model => model.Nick, null, new { @class = "text-danger", @style = "display: block; margin-top: 10px;" })
            </strong>
        </div>
    </div>
    <div class="form-group">
        <label for="Contraseña" class="col-sm-2 control-label">@Html.LabelFor(model => model.Contraseña)</label>
        <div class="col-sm-10">
            @Html.TextBoxFor(model => model.Contraseña, new { @class = "form-control", @placeholder = "Escribe contraseña", @type = "password" })
            <strong>
                @Html.ValidationMessageFor(model => model.Contraseña, null, new { @class = "text-danger", @style = "display: block; margin-top: 10px;" })
            </strong>
        </div>
    </div>
    <div class="form-group">
        <div class="col-sm-offset-2 col-sm-10">
            <button type="submit" class="btn btn-default">Enviar</button>
        </div>
    </div>
}
@section scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

控制器

namespace MundialDeFutbol.Controllers
{
    public class UsuariosController : Controller
    {
        //
        // GET: /Usuarios/
        public ActionResult Index()
        {
            return View();
        }
        public ActionResult Registrar()
        {
            return View();
        }
        [HttpPost]
        public ActionResult Registrar(Usuarios usuario)
        {
            if (ModelState.IsValid)
            {
                var ctx = new MundialDBEntities();
                ctx.Usuarios.Add(usuario);
                ctx.SaveChanges();
                return RedirectToAction("Index","Home");
            }
            return View();
        }
        public ActionResult Login()
        {
            return View();
        }
        [HttpPost]
        public ActionResult Login(Usuarios usuario)
        {
            if (ModelState.IsValid)
            {
                FormsAuthentication.SetAuthCookie(usuario.Nick, false);
                //This needs to be completed I think
                return RedirectToAction("Index", "Home");
            }
            return View();
        }
    }
}

有一些西班牙语单词，抱歉。关键是我使用"Confirmar_contraseña"作为数据库实体模型上的辅助属性，只是为了确认用户键入相同的密码，但是当我尝试登录时，ModelState返回false，我不知道为什么。

if (!ModelState.IsValid)
{
  var errors = this.ModelState.Keys.SelectMany(key => this.ModelState[key].Errors);
  ....