Hi Aakash,
we have the same issue. We also have 7.40 SP11. I think this is a bug. But this is not important enough to us to open an incident yet.
- If DTN is empty it disapperars.
- If I mark it as Always Close it can be opened.
- If I mark it as "Open in new window (standards mode)" DTN is closed but can be opened.
This was tested with classic and AFP/standards.
I would recommend to open an incident if it is important in your case.
Regards, Lutz