NHibernate Sqldatetime must be between 1/1/1753 and 12/31/9999

I am using NHibernate in my MVC project. My problem is when I try to update an object, I get the following error.

Overflow SqlDateTime. Must be between 1/1/1753 12:00:00 and 12/31/9999 11:59:59 PM.

In debug mode I see that the date property is not null. I was setting the Datetime value to display. But I am still getting sqldatetime error.

public class EntityBaseMap<T> : ClassMap<T> where T : EntityBase
{
    public EntityBaseMap()
    {
        Id(x => x.Id).GeneratedBy.Identity();
        Map(x => x.IsDeleted).Not.Nullable();
        Map(x => x.CreatedAt).Nullable();
        Map(x => x.UpdatedAt).Nullable();
        Map(x => x.Random).Formula("NEWID()");

        References(x => x.Status).Column("StatusId");

        Where("IsDeleted=0");
    }
}

      

        
        
        
      

    

Date and time properties are not preserved when saved.

public int SaveOrUpdatePage(PageDto PageDto)
{
    var page = PageDto.Id > 0 ? ById<Page>(PageDto.Id) : new Page();
    var status = PageDto.Status.Id > 0 ? LookupById<Status>(PageDto.Status.Id) : null;
    var type = PageDto.Type.Id > 0 ? LookupById<PageType>(PageDto.Type.Id) : null;
    //var parent = PageDto.Parent.Id > 0 ? ById<Page>(PageDto.Parent.Id) : page.Parent;

    page.Description = PageDto.Description;
    page.Title = PageDto.Title;
    page.SpotText = PageDto.SpotText;
    page.Status = status;
    page.Text = PageDto.Text;
    page.Url = !string.IsNullOrEmpty(PageDto.Url) ? PageDto.Url.ToFileName() : PageDto.Title.ToFileName();
    page.Featured = PageDto.Featured;
    page.Type = type;

    using (var tran = UnitOfWork.CurrentSession.BeginTransaction())
    {
        UnitOfWork.CurrentSession.SaveOrUpdate(page);
        tran.Commit();
    }


    page.CreateDirectory();

    if (PageDto.Id == 0)
    {
        page.Copy();
        page.CopyThumbs();
    }

    SetResultAsSuccess();

    return page.Id;
}

      

        
        
        
      

    

I am using SQLServer 2008 and null resolution datetime table columns columns.