I have never heard of Thieving as a skill, and I am pretty sure that the success of a pickpocket attempt is dependant on the sneak level, the distance to the target and perhaps luck. In any case the chance for succeeding is fracking low.
I have recently decided to play Oblivion again and I am getting really annoyed by the fact that pickpocketing an NPC is so goddamn unrealistic in Oblivion. Even if you have Sneak maxed to 100 and use a spell to give you +300 Sneak for a few seconds and you have over 50% Chameleon at all times and you walk up to a low level NPC (even if he/she is sleeping) and attempt to pickpocket them the chance of beeing detected is irrealistically high. So the only way of beeing successful as a pickpocket is binding Quicksave and Quickload to the left and right mousebutton, because they are the only way of succeeding eventually. I have looked everywhere for a mod that makes pickpocketing more realistic and possible even throws the fracking chanced based system overboard. Does anyone know about a mod for this?