Server Side Validations in MVC4 Models

Question

 public partial class NormalRegistration

    {

        public int Id { get; set; }

        [RegularExpression(@"^[a-zA-Z''-'\s]*$", ErrorMessage = "Please Enter valid Name")]

        [Required]

        [StringLength(50)]

        

        public string Name { get; set; }

         [Required(ErrorMessage = "Email_id must not be empty")]

         [RegularExpression(".+\\@.+\\..+", ErrorMessage = "Please Enter valid mail id")]

        public string Email { get; set; }
}

I am writing validations in models in mvc4 ,i am using regular expressions also.some times are working and sometimes are not working.can you please tell me how to getrid of this problem?