I just got a new Mac Pro and I have a external USB SuperDrive DVD device. It recognizes the DVD device. I am trying to setup Time Machine to do a backup but it does not allow me to select the external DVD device. There is a button to "Select backup Disk" and then there is an option to use disk but it is not enabled. The only thing it does do it search to AirPort devices for Time Capsule. how do I get it to backup to the external DVD device?