There are three version of CS6 two perpetual version and a creative cloud version. If your perpetual CS6 version was updated the the creative cloud version you will most likely need to remove you Creative Cloud software and perhaps download and run Adobe Cleaner so all traces the CS6 version 13.1.2 the Creative Cloud version is removed. The perpetual versions are Platform dependant and will be either Standard or extended depending on you serial. Once you system in clean install you perpetual CS6 you will need your CS6 serial number to activate it and it it a CS6 update you will also need your CS5 serial number. Once you install CS6 you will need to update it CS6 version 13.0 is very buggy without its updates. Also need to install ACR 9.1.1.
After you update CS6 you shoe be a one of the following version levels.
Perpetual Mac CS6 version 13.0.2
Perpetual Windows version 18.104.22.168