If you are using Resources you will need to add the Resources you need to select to the Resources collection of the Slot. For example the sample project can be modified the following way in order to have all the slots of all Resources selected:
sender, RoutedEventArgs e)
var resources = ((
var slot =
Slot(DateTime.Today.AddHours(17), DateTime.Today.AddHours(18), resources);
.scheduleView.SelectedSlot = slot;
Hope this helps.