Tom,
Don't configure the DVD or the CDRW drive on the 3 or 4 channel. You've got RAID set to work on those channels and thereforth the optical media won't work as you need 2 hard disk drives when configuring RAID. Put your DVD and or CDRW on channels 1 or 2 and leave your RAID set on 3 or 4. After doing this you should be able to have access to the optical media and still have your RAID.
jmosher