hi

i am returning to the TOK for the 5th time, and when i get to b9 floor with my round crystal, only the square crystal is there?? the triangle crystal which is meant to be in the treasure chest is gone. the chest is open but the cystal isnt anywhere??? i have started from b1 floor and done every floor again, trying to find where it might be - and its not anywhere???? what do i do??? help!!