Virtual Properties in Modal class are Preventing Validation in MVC

I have create a CRUD Controller by using Entity Framework MVC. In My database i have create some Foreign Relation between tables. By default Entity Framework Create Virtual Properties in Modal Class. Now at the time of page posting It gives a validation Error because, that virtual Properties are null.Realy Need Help. Here brief description of my question.

Model Class Create by Framework

public partial class tbl_Orders_Assigned
{
    public int Assign_Order_Id { get; set; }
    public int Employee_ID { get; set; }
    public int Article_No { get; set; }
..............

    public virtual tbl_Articles tbl_Articles { get; set; }
    public virtual tbl_Employees tbl_Employees { get; set; }
}

Controller

public ActionResult Create()
        {
            ViewBag.ArticleList = new SelectList(db.tbl_Articles, "Article_ID", "Article_ID");
            ViewBag.EmployeeList = new SelectList(db.tbl_Employees, "Employee_ID", "Name");
            return View();
        }


        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create([Bind(Include = "Assign_Order_Id,Date,Employee_ID,Article_No,Gold_Weight_Grams,Gold_Weight_Mini_Grams,Gold_Waste_Issued_Grams,Gold_Waste_Issued_Mini_Grams,IsRecovered,Issued_No")] tbl_Orders_Assigned tbl_Orders_Assigned)
        {
            if (ModelState.IsValid)
            {
                db.tbl_Orders_Assigned.Add(tbl_Orders_Assigned);
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            ViewBag.ArticleList = new SelectList(db.tbl_Articles, "Article_ID", "Article_ID",tbl_Orders_Assigned.Article_No);
            ViewBag.EmployeeList = new SelectList(db.tbl_Employees, "Employee_ID", "Name",tbl_Orders_Assigned.Employee_ID);

            return View(tbl_Orders_Assigned);
        }

View Class

@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()

    <div>
        <h4>ASSIGN NEW ORDER</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })

        <div class="form-row">
            <div class="form-group col-md-4">

                @Html.LabelFor(model => model.Employee_ID, htmlAttributes: new { @class = "control-label " })
                @Html.DropDownList("Employee_ID",(SelectList)ViewBag.EmployeeList, "SELECT EMPLOYEE NAME", htmlAttributes: new { @class = "form-control", autocomplete = "off" })
                @Html.ValidationMessageFor(model => model.Employee_ID, "", new { @class = "text-danger" })

            </div>
            <div class="form-group col-md-4">

                @Html.LabelFor(model => model.Article_No, htmlAttributes: new { @class = "control-label " })
                @Html.DropDownList("Article_No",(SelectList)ViewBag.ArticleList,"SELECT ARTICLE NO", htmlAttributes: new { @class = "form-control" , autocomplete = "off" })
                @Html.ValidationMessageFor(model => model.Article_No, "", new { @class = "text-danger" })

            </div>
        </div>

    .......................... Other Model Code

    </div>


    <div class="form-row">
        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-outline-success" />
            </div>
        </div>
    </div>

}

Error Image