Redoing A Shantotto Accension Reward

So I read how to redo the prize selection and it said to drop ur current selection, buy the seeds from the goblin in port jueno, go and redo fight. After the fight, I only got one key, not the behemoth key that I needed to trade in the tenshendo. Is there something else I need to do to get that key again?

What did you get if not the behemoth key? Did you drop the pants first?

after the battle, i didnt get a behemoth key for a key item, got the tonberry key and thats it. then i traded tonberry key to the chest in tensendo and got a piece of iron.

before all of this, i tossed the body first just like BG said to.

And why would you drop a body piece that had nothing to do with the missions in question?

you're right! i drop the wrong reward piece...

Looking at the wiki, you get the Tonberry Key at the end of the fight. You get the Behemoth Key from the next cutscene, by zoning into Windy Walls from Windy Woods or Windy Waters

Nevermind, the last mission says you get both after the fight when you are redoing it.