Mac Pro optical drive

I have a Mac Pro desktop quad xeon, and I cannot get the optical drive to read a +R double layer disk. Nothing shows up on the desktop or anywhere else. Can anyone throw some light on this problem, I would appreciate it. Thanks

The optical drive could be having problems even though it may be able to read and write to single layer DVDs and CDs. It takes a greater amount of optical power to read and write to double layer disks. Unfortunately, slot loading drives used in Macs are more susceptible to failure than tray loaders.

Also try another double layer disk. The one you're trying to read could be bad.

Thought OP said a Mac Pro. Am I missing the iMac bit?

Sounds like the optical drive is failing. In Apple System profiler, what does it say about Disc Burning and DVD Write? Even an older optical drive in say a G4 can read Dual Layer discs, but of course not burn them.