ActionFilter中奇怪的无效强制转换异常

我有一个自定义动作过滤器，它将在我的控制器中使用[log]属性自动记录用户的动作。我在多个应用程序中使用了相同的设置，所以我知道它可以工作，但这次失败了，我不知道为什么。

    public override void OnResultExecuted(ResultExecutedContext thisContext)
    {
        LogTrace(thisContext.RouteData);
    }
    public void LogTrace(RouteData routeData)
    {
        MyContext db = new MyContext();
        TimeSpan Duration = (DateTime.Now - StartTime);
        string Controller = ReadableController((string)routeData.Values["controller"]);
        string Action = (string)routeData.Values["action"];
        long? ID = (long?)routeData.Values["id"];
        LogFile log = new LogFile();
        log.UserID = User.ID;
        log.Controller = Controller;
        log.Action = Action;
        log.ItemID = ID; 
        log.Timestamp = DateTime.Now;
        log.Duration = Duration;
        db.LogFiles.Add(log);
        db.SaveChanges();
    }

我得到'指定的cast是无效的' LogFile log = new LogFile().

long? ID = (long?)routeData.Values["id"];