MVC - Foreign Key Error because of ViewModel? - asp.net-mvc-4

Question

I am Creating View Model of Employee Class and strongly typed my Create View with the EmployeeViewModel. In future, I will add many classes in my View Model. But the problem is I am getting Gender Foreign Key Error. May be I am binding wrong values in Create Controller. Below is my code:
Create Controllers:
public ActionResult Create()
{
ViewBag.GenderId = new SelectList(db.Genders, "Id", "Name");
return View();
}
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(EmployeeViewModel employeeModel)
{
if (ModelState.IsValid)
{
db.Employees.Add(employeeModel.Employee);
db.SaveChanges();
return RedirectToAction("Index");
}
ViewBag.GenderId = new SelectList(db.Genders, "Id", "Name", employeeModel.Employee.GenderId);
return View(employeeModel);
}
Create View:
#model WebApplication2.EmployeeViewModel
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>Employee</h4>
<hr />
#Html.ValidationSummary(true, "", new { #class = "text-danger" })
<div class="form-group">
#Html.LabelFor(model => model.Employee.Name, htmlAttributes: new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.EditorFor(model => model.Employee.Name, new { htmlAttributes = new { #class = "form-control" } })
#Html.ValidationMessageFor(model => model.Employee.Name, "", new { #class = "text-danger" })
</div>
</div>
<div class="form-group">
#Html.LabelFor(model => model.Employee.GenderId, "GenderId", htmlAttributes: new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.DropDownList("GenderId", null, htmlAttributes: new { #class = "form-control" })
#Html.ValidationMessageFor(model => model.Employee.GenderId, "", new { #class = "text-danger" })
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}
Models:
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
public byte GenderId { get; set; }
public Gender Gender { get; set; }
}
public class Gender {
public byte Id { get; set; }
public string Name { get; set; }
}
View Model:
public class EmployeeViewModel
{
public Employee Employee { get; set; }
}