Feed The Language Culture Thread Into The Helper Class?

With asp.net MVC 2, I have been trying to get Matt Hawley's Localization helper to work in my web application, but I am getting stuck feeding a null into the Language string variable. I can't figure out why I am doing this.

namespace MvcLocalization
{
public abstract class LocalizedControllerBase : Controller
{
public String LanguageCode { get; private set; }
protected override void Initialize(System.Web.Routing.RequestContext requestContext)
{
LanguageCode = requestContext.RouteData.Values["languageCode"].ToString();
if ( !AppConfig.SupportedLanguages.Contains(LanguageCode) )
LanguageCode = AppConfig.DefaultLanguageCode;
System.Globalization.CultureInfo culture = System.Globalization.CultureInfo.CreateSpecificCulture(LanguageCode);
Thread.CurrentThread.CurrentCulture = culture;
Thread.CurrentThread.CurrentUICulture = culture;
base.Execute(requestContext);
}
}
}