Thank you for contacting us again.
Unfortunately we could not reproduce the unusual issue locally but from your description it is most probably caused by some not proper loading of the client scripts of RadScheduler in SharePoint. That is why would you please try to load them programmatically as it is done in the attached sample web part. Please let us know if you still observe the issue or you have further questions.
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to the blog feed