Why CDs won't open on my MacPro external CD player

Have a MacPro with Sonoma 14.4. Bought an Apple USB SuperDrive. I've put in over 30 disks and they all come back with "The disk you attached was not readable by this computer." They can't all be corrupted. I've tried Disk Utility. Nothing. Am I doing something wrong???

[Re-Titled by Moderator]