help please...

okey doke.....im up to the part where kuja holds u prisoner in disc 3 and tells u to go retrieve the gulug stone...then after that you control the second party and you have to escape his palace....i've read all these walkthroughs on the internet and they say to light the final candle at the top of the castle to activate the security system or something?..i've lit all the candles, but when i get to the very top i can see the last candle but i cant light it...as in the "!" wont appear...did i miss something coz i figure out why it wont light.....my party is steiner vivi freya and quina..(chose them coz they needed to level up)...any help would awesome

EDIT

oh yeah....i just found out where i screwed up...when you're at the library you'r supposed to go through the middle shelves to light the candle up thoses stairs....i remember it opening but i went to go save and then it was sealed......is there a way to reopen it?