对象引用未设置为对象的实例

我正在构建一个具有多层的WCF应用程序，在尝试向DB添加新对象时遇到了此异常。我将为您提供代码示例，请尝试在这里帮助我。错误出现在scenaristBLL.Insert(s); 线上

以下是我的方法，我试图在ScenaristController类中创建一个新的Scenerist对象：

[HttpPost]
        public ActionResult Create(ScenaristViewModel fvm, List<int> scenarijId)
        {
            if (fvm != null)
            {
                if (String.IsNullOrEmpty(fvm.Scenarist.NameSurname) == true)
                {
                    TempData["ValidationErrorIme"] = "validation err1";
                    return RedirectToAction("Create");
                }
                if (fvm.Scenarist.DateOfBirth == null)
                {
                    TempData["ValidationErrorGodina"] = "validation err2";
                    return RedirectToAction("Create");
                }
                Scenarist s = new Scenarist();
                s.NameSurname = fvm.Scenarist.NameSurname;
                s.DateOfBirth = fvm.Scenarist.DateOfBirth;
                s.dateOfDeath = fvm.Scenarist.dateOfDeath;
                scenaristBLL.Insert(s); // PROBLEM!
                s = scenaristBLL.Fetch(s.Id);
                foreach (int scenarij in scenarijId.Where(z => z != 0))
                {
                    Scenarij scn = scenarijBLL.Fetch(scenarij);
                    if (scn == null)
                    {
                        return new HttpNotFoundResult("Nepostojeći scenaristId: " + scenarij.ToString());
                    }
                    scenarijBLL.AddToScenarist(scn, s);
                }
            }
            return RedirectToAction("Index");
        }

此外，这是它的View类：

<table>
            <tr>
                <td>Name and surname:</td>
                <td>@Html.TextBoxFor(modelItem => Model.Scenarist.NameSurname) @TempData["ValidationError1"]</td>
            </tr>
            <tr>
                <td>Date of birth:</td>
                <td>@Html.TextBoxFor(modelItem => Model.Scenarist.DateOfBirth) @TempData["ValidationError2"]</td>
            </tr>
            <tr>
                <td>Datum of Death:</td>
                <td>@Html.TextBoxFor(modelItem => Model.Scenarist.DateOfDeath) @TempData["ValidationError3"]</td>
            </tr>
        </table>

我认为DateOfBirth和DateOfDeath可能是个问题，因为它们是DateTime格式的，我不知道如何从用户输入中获得DateTime格式。只是猜测，真的不确定。

此外，这里还有其他层次。。。BLL:

public void Insert(Scenarist scenarist)
{
    string error;
    if (scenarist.Validate(out error) == true)
    {
        string[] nameSurname = scenarist.NameSurname.Split(' ');
        string name = nameSurname[0];
        string surname = nameSurname[1];
        dal.Insert(name, null, surname, scenarist.DateOfBirth, scenarist.DateOfDeath);
    }
    else
    {
        throw new ArgumentException("Validation error: " + error);
    }
}

DAL:

public void Insert(string name, string middleName, string surname, 
    DateTime? dateOfB, DateTime? dateOfD)
{
    using (RPPP111Entities ctx = new RPPP111Entities())
    {
        Scenarist scenarist = new Scenarist();
        scenarist.Person.Name = name;
        scenarist.Person.Middlename = middleName;
        scenarist.Person.surname = surname;
        scenarist.Person.DateOfB = dateOfB;
        scenarist.Person.DateOfD = dateOfD;
        ctx.Scenarist.Add(scenarist);
        ctx.SaveChanges();
    }
}