FullCalendar on JQueryWidgetBox not work

Regards, I use Seaside 3.1, Pharo 3.0,  on Ubuntu 14.04.I need to use fullcalendar on JQWidgetBox but does not work. When I try to access it with url:     http://localhost:9090/jquery-widgets/fullcalendar Error message is: MessageNotUnderstood:  receiver of "encodeCollection:on:" is nil Thanks for the support Oswall