Why won't Roxio detect DVDR?

I just got a brand new Dell Latitude last week. I copied a DVD to a disc image file and tried to burn the disc image. I've tried 3 different DVD brands and every time it's the same thing: the disk drive shows that there is a blank DVD in the drive, but when I go to burn the file, it asks me to insert a blank DVD. These DVDs are brand new! Does anyone have any suggestions?