I isolated the demo in a user control and things work fine with me. I am attaching here the simple page I used for testing and a screen capture of how things work with me,
and connection string you can obtain from the demos (Telerik.mdf and TelerikConnectionString from the web.config).
Can you compare this page with yours and see where the major differences are? For example tooltip manager settings, or the way appointments are added (if the incorrect element is added it will not throw the proper mouseover event and will not pass the expected data).
I suggest you examine my page and use it as base for getting this functionality running in your case.
Alternatively, you can go for a client-side approach as shown in this code library entry
All the best,
the Telerik team
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