Hello Ha,
Thank you for your reply.
Without having access or at least the source of your application we cannot investigate further. We tried to execute your code against a sample table and it runs without the error: System.NullReferenceException: Can't Find Items tblFunction. Here is a short video demonstrating how this is working on our side. I am also attaching my test for further references. in this ticket.
It seems you are getting the error because you are using a different table id or the id got changed for some reason. In case everything is set correctly and the problem is on our side, this might be specific issue and we still need access to your application in order to get a repro and continue investigating on our side.
Regarding the missing <tr> tag are you sure you are pointing the right table, but not an empty one?
Once again without access or stripped down version of your application we cannot continue investigating any further.
Thank you for your understanding regarding this matter.
Regards,
Ivaylo
the Telerik team