My Controller to DropdownList returns with failed to load resource: the serve responded with a status of 500 ()

I’m trying to make cascading dropdowns. The first one works fine but the second is not getting the data from the controller. The DeptID passes through to my GetStores parameter fine, but does not populate the second dropdown.

public ActionResult HistoryView()
{
  var model = new TemplateViewModel();
  model.Depts = _uow.Repository<Dept>().GetAll();

  ViewBag.listCompanies = new SelectList(_uow.Repository<Dept>().GetAll(),"DeptID","Dept_Name");

  return View(model);
}

public JsonResult GetStores( int DeptID)
{
  TemplateViewModel templateViewModel = new TemplateViewModel
  {
    Dept = _uow.Repository<Dept>().Get(x => x.DeptID == DeptID),
    Templates = _uow.Repository<Template>().GetAll().ToList()
  };
  return Json(templateViewModel, JsonRequestBehavior.AllowGet);
}

<div style="background-color:azure; border-color:black; border:solid">
  <br />
  <div>
    <b>Select your Company:</b>
  </div>
  <div>
    @Html.DropDownList("DeptID", (IEnumerable<SelectListItem>)ViewBag.listCompanies,String.Empty,  new {style = "width: 200px;"})
  </div>
  <br />
  <div>
    <b>Select Store</b>
    <div>
      @Html.DropDownList("TemplateID", new SelectList(string.Empty, "Value", "Text"), "--Select Store--", new { style = "width:200px;" } )
    </div>
  </div>
</div>
<script>
  $(document).ready(function() {
    $("#DeptID").change(function() {
      $("TemplateID").empty();
      $.getJSON('/HistoryLog/getstores', { DeptID: $('#DeptID').val() }, function(data) {
        $.each(data, function () {
          $('#TemplateID').append('<option value=' + this.Value + '>' + this.Text + '</option>');
        });
      });
    });
  });
</script>