Auto transmission will not up shift could this be electric or plantar gears

The transmission can be scan tested to confirm if it an electrical problem or not .. Then other test can be performed to confirm if it's a mechanical problem .. Why not take advantage of this technology? .. You'll save money in the long run! .. Any other answer you get is just going to be a guess, that don't help! .. Testing is the key to any 'successful' repair .. Now 'IF' you have access to the necessary equipment and have the skills, we can help! .. Good luck with it.