There is no viewdata item of type ienumerable<selectlistitem> that has the key?

private IEnumerable<SelectListItem> GetCountryList()
  {
      SelectList listcn = null;
      try
      {
          var list = this.LoadData().Select(p => new SelectListItem
          {
              Value = p.Country_Id.ToString(),
              Text = p.Country_Name
          });
          listcn = new SelectList(list, "Value", "Text");

      }catch(Exception ex)
      {
         // throw ex;
      }
      return listcn;
  }

   private List<EditTrainingRegFormViewModel> LoadData()
{
    List<EditTrainingRegFormViewModel> lst = new List<EditTrainingRegFormViewModel>();

    try
    {
        string line = string.Empty;
        string srcFilePath = "Content/files/country_list.txt";
        var rootPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().CodeBase);
        var fullPath = Path.Combine(rootPath, srcFilePath);
        string filePath =  new Uri(fullPath).LocalPath;
        StreamReader src = new StreamReader(new FileStream(filePath, FileMode.Open, FileAccess.Read));

        // while to read the file
        while((line = src.ReadLine()) !=null) {
          EditTrainingRegFormViewModel infoLst = new EditTrainingRegFormViewModel();
            string[] info = line.Split(',');

            //Setting
            infoLst.Country_Id = Convert.ToInt32(info[0].ToString());
            infoLst.Country_Name = info[1].ToString();

            lst.Add(infoLst);
        }
        src.Dispose();
        src.Close();
    }catch(Exception ex)
    {
        Console.Write(ex);
    }
    return lst;
}

// Selection for countries in the world.

      public ActionResult DropDownSelect()
      {
          EditTrainingRegFormViewModel model = new EditTrainingRegFormViewModel();

          model.SelectedCountryId = 0;

          this.ViewBag.CountryList = this.GetCountryList();
          return this. View(model);
      }

@Html.DropDownListFor(m=>m.SelectedCountryId, this.ViewBag.CountryList as SelectList, new {@class = "form-control"})