trouble code

I have been having problems with the engine light coming on now so I finally went to get it read and it is the code PO733 which is incorrect ratio gear 3. So somethings going on with my 3rd gear im guessing and thats why it just revvs and wont switch gears. Can anybody tell me more about this like what could be wrong..would be wrong.Any kind of information on this would be greatly appreciated. Thanks
Its a 96 Sc2 Automatic

assuming you've never had the transmission replaced, there is something wrong inside the transmission causing 3rd gear to slip. a common problem for the S-series auto trans is the nut on the end of the input shaft coming loose, causing gears to slip and also slaming into gear. if the input shaft nut is at fault, it can be done by an advanced home mechinic(special tools are required) or at a saturn dealership for somewhere in the area of $700(i would not trust the job to a indepentant trans shop). other possibitys are worn clutch packs or a hydraulic problem.

ok thanks thats probably it...it shifts into gear pretty hard but its been doing that since i got the car 3 years ago and about 48,000 miles ive put on it and now its showing a code finally..But thanks