CyrstalReport DataSet doe not support Nullable?

Question

Hi Team

 

I have a controller and getting an error "DataSet does not support System.Nullable" How can i solve this issue?

 

// Controller
public ActionResult Download_XMLReport()
        {
            eNtsaRegistration context = new eNtsaRegistration();

            ReportDocument rpt = new ReportDocument();
            rpt.Load(Path.Combine(Server.MapPath("~/Reports"), "AcademyReports.rpt"));
            rpt.SetDataSource(db.TrainingRegs.ToList());  // DataSet Does not support system.nullable??
            Response.Buffer = false;
            Response.ClearContent();
            Response.ClearHeaders();

            rpt.PrintOptions.PaperOrientation = CrystalDecisions.Shared.PaperOrientation.Landscape;
            rpt.PrintOptions.ApplyPageMargins(new CrystalDecisions.Shared.PageMargins(5, 5, 5, 5));
            rpt.PrintOptions.PaperSize = CrystalDecisions.Shared.PaperSize.PaperA5;

            Stream stream = rpt.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);
            stream.Seek(0, SeekOrigin.Begin);




            return File(stream, "application/xml", "eNtsaReportTrainingForm.xml");
        }

// Model DbContext
public class eNtsaRegistration:DbContext
    {

        public eNtsaRegistration() : base("eNtsaRegistration")
        {
        }  public DbSet<TrainingRegForm> TrainingRegs { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            Database.SetInitializer<eNtsaRegistration>(null);
            base.OnModelCreating(modelBuilder);
        }
    }
// Table-Definition
public class TrainingRegForm
    {
        [Key]
        public Guid? Id { get; set; }
        public string Title { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Position { get; set; }
        public string Company { get; set; }

        public string StreetAddress { get; set; }

        public string StreetAddressLine { get; set; }

        public string City { get; set; }
        public string StateProvince { get; set; }

        public int ZipCode { get; set; }

        public string Email { get; set; }

        [Required(ErrorMessage = "This field is required")]
        [DataType(DataType.PhoneNumber)]
        public string CellNumber { get; set; }
        public string DietaryRequirement { get; set; }
    }