Lost

I am having a devil of a time. I am trying to copy the shield to a dual layer dvd. I have a dual layer dvd in my external dual layer burner it is a lite on I forget the model number but bought less then 6 months ago. I am using my internal player to copy to the external. I have tried to copy using DVD5 and or DVD 9. Each time I get the error no media inserted I have tried everything I can think of. I have gotten it to work on other burns of disks but can’t remember what I did. How do I get started on correcting the problem. :confused: