Are you connecting the Super Drive directly to the laptop?
Try using another USB port. Disconnect all other external devices.
Try an SMC reset and a PRAM reset (hold the PRAM reset for a full minute so it activates several times).
Are the discs pre-recorded from the factory or discs someone has burned?
Are you trying to mount a CD or DVD? Try other discs and try at least on CD and one DVD since the Super Drive may be able to read one type and not another type.
Check the bottom of the disc for dirt or scratches. The worst type of scratches are ones which circle around the disc like the grooves on a vinyl record. Deep scratches are also bad. Are there any discolorations or blemishes in the "platter" which might indicate the disc is deteriorating?
Maybe the SuperDrive has a dirty lens.
Try the discs with another optical drive. Try the Super Drive on another Mac if you have access to one.
Movie DVDs and some audio CDs and game/software discs incorporate DRM so people cannot copy the discs which can sometimes cause problems with some optical drives.