Whenever something like this happens to me, I look up the guide and use everything as a checklist to make sure I got it all done. Here's the guide from FFXIcyclopedia from Wikipedia:
* Accept the Mission (turn in some crystals if they don't offer it immediately).
* Go to Heavens Tower and talk to Kupipi. She will give you access to the upstairs regions of the Tower.
* Go through the doors to the left of Kupipi and go all the way to the very top (third) floor.
* At the top, speak to Rhy Epocan for a cut-scene.
* Leave Heaven's Tower (there is a glowing blue light that is a transporter that will take you to the bottom floor) and go to the Orastery in Port Windurst. Talk to Hakkuru-Rinkuru at E-7. (This may be the one you forgot, if you forgot anybody. Try him again to be safe, and maybe even the taru standing next to him as well)
* This is a good time to also do the Onion Rings quest. (not required to do the mission, but you'll be down in that hole anyway. You don't have to have the quest flagged to get the cutscene).
* Go out to Castle Oztroja. At level 30, the mobs will mostly be Easy Prey, but Sneak/Invis is still a good idea just because there are so many of them. And it's highly recommended that you bring a Scroll of Instant Warp to get out easily.
* Go to the door at I-8. Pull the 2 levers until a trap door opens beneath you. You must stand between the 2 levers to drop down. If the mobs will still aggro you here, just be patient and wait for all the Yagudo to face away from you. Then cancel Invis and hit the lever.
* After the cut-scene you'll be in I-8 on this map (the small sliver on the right side). If you're doing the Onion Rings quest, this is where the ??? that you get the ring from is located.
* Either make your way out of the Castle, or use your Warp if you brought one.
* Go back to Heaven's Tower and talk to Rhy Epocan to finish the Mission.
Note: If being assisted or assisting someone on this mission, the individual who has the mission flagged must hit the lever to get the cut-scene.
Note the note.
You, sir, have to be the one to hit the lever. If anyone else in the party has been hitting it, that would have been your problem right there. Otherwise, I don't know how it can be helped. Good luck
