Thank you for your reply.
I converted the example also and tested it. The reason for the exception is that when you start the project, the first page view is created, its pages are added and its SelectedPage property is set. This setting fires the event and it tries to set the SelectedPage of the second page view, but this page view has not been initialized yet and its pages have not been added to its pages collection. To work around this, please subscribe to the event after the form components have been initialized. This means after the call to the InitializeComponenets method in the form constructor.
I hope this will be useful for you. If you have further questions, I would be glad to help.
the Telerik team