A blank cd is not like a ‘blank’ floppy. A floppy normally is already formatted and has a mbr. A blank cd has nothing on it. So you can ‘scan’ a blank floppy but not a blank cd.
You can also ‘scan’ a formatted (but empty) cdr, dvdr, memstick etc. It wil just say that there are no files to scan.
But you can’t scan a blank cd or dvd. Anything that hasn’t already have a ‘format’ can’t be scanned.