Recurrence error in JavaScript with MVC

OK I have got a form which uses this code, but the recurrence doesn’t work if I add a custom item (in this case ‘Priority’)

I get this error:
dhtmlxscheduler.js:257 Uncaught TypeError: Cannot read property ‘id’ of undefined

public ActionResult Index()
var data = new SampleDataContext();
var scheduler = new DHXScheduler(this); //initializes dhtmlxScheduler

        var select = new LightboxSelect("textColor", "Priority");
        var items = new List<object>(){
            new { key = "gray", label = "Low" },
            new { key = "blue", label = "Medium" },
            new { key = "red", label = "High" }
        select.MapTo = "color";

        scheduler.Lightbox.Add(new LightboxText("text", "Description"));
        scheduler.Lightbox.Add(new LightboxRecurringBlock("rec_pattern", "Recurring"));

        scheduler.LoadData = true;// allows loading data
        scheduler.EnableDataprocessor = true;// enables DataProcessor in order to enable implementation CRUD operations
        return View(scheduler);

when you use a recurring control, the time control is required as well. E.g. please check a working demo …