ASP.Net MVC - Losing DropDownList client validation styles and new SelectList default not working

Question

When I populate a DropDownList with data in the View .aspx my validation styles are applied when I submit without selecting from Country DropDownList.

In my web model I have this:

[DisplayName("Country")]
[Required(AllowEmptyStrings = false, ErrorMessageResourceName = "ListingPost_FK_Country_CodeRequired", ErrorMessageResourceType = typeof(ErrorMessages))]
public string Country { get; set; }

In my View is this:

Html.DropDownList("Country", new[] { 
                  new SelectListItem { Text = "US", Value = "US" },
                  new SelectListItem { Text = "Canada", Value = "CA" },
                  new SelectListItem { Text = "Outside US/Canada", Value = "-1" }, },
                  "Please Select")

If I submit without picking a country my DropDownList get a red border and all is well.

But when I populate the DropDownList in code I lose the validation (red border) with no country picked. The ModelState.IsValid is false but why am I losing client validation style?

IQueryable countries = null;

using (MyEntities context = new MyEntities())
{
   countries = from country in context.Countries
               select country;
   List countryList = countries.OrderBy(c => c.Description).ToList();
   Country countryDefault = countryList.FirstOrDefault(c => c.Country_Code == "US");

   ViewData["Country"] = new SelectList(countryList, "Country_Code", "Description", countryDefault);
}

Also, my default Country object is not being set. When populating in C#, it's defaulting to the first item in list and should be defaulting to US.

Thanks...