C# - To Change NewReservation.SelectedServiceDate From DateTime To String?

I'm having problems with the helper Html.ListBoxFor().

Here is my ViewModel:

public class NewReservation
{
public SelectList AvailableServiceDates { get; set; }
public DateTime SelectedServiceDate { get; set; }
}


Here is my action method:

public virtual ActionResult New()
{
NewReservation newReservation = new NewReservation(); [code]....

And in my view:<%:Html.ListBoxFor(x => x.SelectedServiceDate, Model.AvailableServiceDates) %>

Here is the exception: Value cannot be null.

Parameter name: source

Stack Trace: [ArgumentNullException: Value cannot be null. Parameter name: source] System.Linq.Enumerable.Cast(IEnumerable source) +4177011 System.Web.Mvc.Html.SelectExtensions.SelectInternal(HtmlHelper htmlHelper, String optionLabel, String name, IEnumerable1 selectList, Boolean allowMultiple, IDictionary2 htmlAttributes) +723

This post describes the same problem. And like that post, if I change my NewReservation.SelectedServiceDate from DateTime to string, things seem to work. But everything I have read indicates this is a bug that should have been fixed in an MVC2 release candidate.

Am I doing something wrong? I don't want the property's type to be string, it needs to be DateTime. Shouldn't I be able to use objects that reflect my problem?