Hi Navaneethan,
There can be a lot of reasons for this, most common is that your element is not ready yet. Insert a wait stage to wait for the element before reading/writing to it.
Another common problem is that your VDI uses a different resolution than the desktop you debugged on. You should make an RDP to the VDI, see it run successfully through the control room in unattended mode. If this work, try to run it again after restarting the VDI and not being logged in. IF it fails while you are logged in, something is different on the VDI than on your Test Desktop. IF it succeeds while you are logged in AND fails on running while you don't look(RDP to it), the chances are quite high it's a resolution problem.
Good luck debugging 🙂
Frank