Validate custom file type using data aotation validator

I have a simple form that will upload multiple files. I have created a custom file type in order to store other relevant data in the upload and i am trying to validate the files uploaded but the model fails to bind from my custom file type so the model.isvalid always retus false

So i am trying to create a custom validation override that will work with my file structure but the value is always empty and i cant figure out the reason.

The file property is :

    [Required(ErrorMessage = "Please select a file to upload")]
    [Display(Name = "Upload Files")]
    [ValidateFile]
    public virtual ICollection<UserFile> Files { get; set; }

    public class ValidateFileAttribute : ValidationAttribute
    {
        public override bool IsValid(object value)
        {
            int MaxContentLength = 1024 * 1024 * 3; //3 MB
            string[] AllowedFileExtensions = new string[] { ".csv" };
            var files = value as ICollection<UserFile>;
            foreach(var asd in files){
                var file = value as HttpPostedFileBase;

                if (file == null)
                    retu false;
                else if (!AllowedFileExtensions.Contains(file.FileName.Substring(file.FileName.LastIndexOf('.'))))
                {
                    ErrorMessage = "Please upload Your File of type: " + string.Join(", ", AllowedFileExtensions);
                    retu false;
                }
                else if (file.ContentLength > MaxContentLength)
                {
                    ErrorMessage = "Your File is too large, maximum allowed size is : " + (MaxContentLength / 1024).ToString() + "MB";
                    retu false;
                }
            }
            retu true;
        }
    }

Custom type UserFile is defined as:

public class UserFile
{
  [Key]
  public Guid FileId { get; set; }
  [StringLength(255)]
  public string FileName { get; set; }
  [StringLength(100)]
  public string ContentType { get; set; }
  public string Path { get; set; }
  public FileType FileType { get; set; }
  public virtual User User { get; set; }
}

My controller validation includes:

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Send(User user,  IEnumerable<HttpPostedFileBase> Files)
        {
            try
            {
                if (ModelState.IsValid)
                {

I can use the Files from the post here but still the model validation fails.

Thank you in advance for any help, as i am trying to lea more about this type of validation. please let me know if further information is required