Hello Le Corbu,
"When selecting such a page from result I got the "This type of page is not served" error message."
If the user you use does not have permissions to see this page, it is normal to see this error. The problem here is that we do not check the page permissions and exclude these pages from the index.
I logged a request for this implementation with ID - 106285
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items