Dropdown Required and Display attribute not working

Question

Can we make dropdown required to select which is binding using ViewBag as below-

// GET: Employee/Create in the action method
public ActionResult Create()
{
ViewBag.DepartmentId = new SelectList(db.Departments, "Id", "Name");
return View();
}
// GET: Employee/Create in the Create view
@Html.LabelFor(model => model.DepartmentId, "DepartmentId", htmlAttributes: new { @class = "control-label col-md-2" })
@Html.DropDownList("DepartmentId", null, "Select Department", htmlAttributes: new { @class = "form-control" })
@Html.ValidationMessageFor(model => model.DepartmentId, "", new { @class = "text-danger" })

// setting metadata
[MetadataType(typeof(EmployeeMetaData))]
public partial class Employee
{
}
public class EmployeeMetaData
{
[Required]
public int EmployeeId { get; set; }
[Required]
public string Name { get; set; }
[Required]
public string Gender { get; set; }
[Required]
public string City { get; set; }
[Required]
[Display(Name = "Department")]
public Nullable<int> DepartmentId { get; set; }

i have set attribute Required and Display but both are not working,

 

pls help me.