I've never used DVD shrink, so don't know about that, I prefer
dvd2one.
It sounds like the dvd-r you are using is not recognised by your writer. You will need to check the manufacturers website for a compatability list, you may need to do a firmware update to get it to recognise the disks you are using. Just because it is a dvd-r doesn't necessarily mean your drive can recognise it I'm afraid.