EDIT: I just saw that you got a few sensible new replies in ABO's thread, so some of my writing is redundant. Anyway, I let it stay in case you still get it not working.
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Another quick idea: You say the leveling bar is stuck at zero. But using the skills, like throwing a Light spell or Healing spell for 30 times or conjuration spell... does your experience advance in that skill? Maybe your skill does increase, but only the bloody bottom bar is stuck at zero? Or are the individual skill bars (for like Illusion) also stuck at zero?
Now if this is also yields no result... then I think we do have a problem...
I know you have reinstalled or at least deactivated and re-enabled your mods about 50 times by now and are probably sick and tired of it. But have you done the ultimate test: Uninstall
and erase / delete your present Oblivion folders alltogether and re-install only the base game, with at maximum only SI in addition because of the 1.2.416 patch (if you have GOTY edition for example). So no other DLC contents, no extra textures, no sixy bodies, no user interface, even no Darnified, no hotkeys, no Bashed Patch, NO NOTHING OF ANYTHING. Vanilla, vanilla, vanilla only! Kick out all the OBSE plugins and OSR, Streamline and everything. Only retain the new OBSE v18 beta 6. I'm using it, it's working fine with RL.
Then install UOP and 3.2.4 hotfix (and possibly the USIP). http://i35.photobucket.com/albums/d191/haegint/Oblivion/BasicModlist01.jpg. I just x-ed out OOO.esm for now. Then only add RL as the only "real" mod. So your modlist should be only 5 entries long. Then fire up a new game, create a new character, do the tutoria dungeon. Then RL MUST work. It cannot BUT work. Yeah I know I sound silly. But if it would not, really, you'd be the only person in all Tamriel.

It's obviously the most radical thing to do, so you dislike it, and I fully understand. But think of this: The fact that RL is just not working raises my suspicion that there MUST be some defect SOMEWHERE with your installation elsewhere. Now I'm not God, so I can't be sure. BUT... for I dare say most people including myself, that bloody RL was working even when added to an ongoing game with some mods already present.
So with a clear mind and possibly some days of distance, I'd go again at the problem starting really from below-zero as I have outlined. I'm sorry that your patience is tested so much with this. But again, the fact that RL is just not working is - in my mind - actually a pretty troubling sign with regard to your whole Oblivion installation. You remember Mr. Spock and his irrefutable logic? This is how I feel about it by now. I mean you have the problem like for a week now which is getting ridiculous. You don't want to build a Space Shuttle, it's only RL!! Please do understand that I'm not bashing you or questioning you in any way! I actually feel pretty bad because I fear I am speaking "the inconvenient truth"... so please forgive me. :foodndrink: