What is wrong with my model? [EmailAddress] namespace could not be found?

Question

I installed data annotations MVC3 (I am using MVC3) and my [EmailAddress] data annotation cannot be found. I searched online and I do not understand why it is not referencing.

Here is my model:

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

    namespace Projectx.Models
    {

        public class PreSignUpUser
        {
            [Required]
            [EmailAddress]
            public string Email { get; set; }
        }
    }

Can someone help me out?

Answer 1

Maybe try this:

[DataType(DataType.EmailAddress)]

in place of

[EmailAddress]