asp.net mvc 3 - Why is ValidationSummary(true) displaying an empty summary for property errors?

Question

I am having a slight issue with the use of ValidationSummary(true) to display model level errors. If the ModelState does not contain model errors (i.e. ModelState.AddModelError("", "Error Description")) but contains property errors (added using data annotations) it displays the validation summary with no error information (when you view the source). My css is therefore displaying an empty red box like so:

If there are no property errors then no validation summary is displayed. With ValidationSummary(true) I would expect it to only display validation errors if there are model errors. What have I misunderstood?

I have a basic project as follows:

Controller:

public class HomeController : Controller
{
    public ViewResult Index()
    {
        return View();
    }

    [HttpPost]
    public ActionResult Index(IndexViewModel model)
    {
        return View();
    }
}

Model:

public class IndexViewModel
{
    [Required]
    public string Name { get; set; }
}

View:

@model IndexViewModel

@Html.ValidationSummary(true)

@using(@Html.BeginForm())
{
    @Html.TextBoxFor(m => m.Name)
    <input type="submit" value="submit" />
}

Answer 1

@if (ViewContext.ViewData.ModelState.Where(x => x.Key == "").Any())
{
    @Html.ValidationSummary(true, null, new { @class = "ui-state-error" })
}

This checks if there are any model wide errors and only renders the summary when there are some.