FFX Problem (maybe Spoilers)

Okay, I’ve unlocked Nemesis in the arena before, but for some reason, I decided to do the quest again. But now, I have run into a strange bug; I’ve caught 10 of each monster from each region from each species, and I have defeated and then re-defeated every Species Conquest, Area Conquest and Original Creation. But Nemesis will not appear. Any ideas on what to do? I’d hate to lose this file to a glitch; I’ve got Tidus done the Sphere Grid, every weapon powered fully, and Auto Haste on every character.

Are you sure you got ten of both kinds of Gemini?

I’m sure, because you can’t unlock Ultima Buster until you do just that. But I like your way of thinking; thanks for your input. 8)

Anyone else?

Are you totally sure you have beaten all of the other monsters you need to?

If that ain’t it, I’m out of ideas.

I’ll try again, but Thu’ban is such a hassle… I didn’t really add anything to the Grid so that I could keep track of stats easier. Thanks for your help, anyways. 8)