Help with stupid treasure chest in Cleyras Trunk!!!

So I'm in Cleyras trunk, and I just fliped the switch to make the room below fill with sand... you know, the switch. Anyway... when I go to the room below, there is a treasure chest on a little ledge above me. I'm sure somebody knows what treasure chest I'm talking about. I can't seem to get up on that ledge. It kind of looks like there is an entrance to the ledge from the outside, but there are no vines I can climb or anything like that to get any higher than I already am. Also in the room, there is a hanging root that goes from the opposite side of the area to the ledge. I thought maybe I could get on the root somehow, but that doesn't seem to work either. Hopefully somebody can help me out.

If anybody doesn't know what area I'm talking about, just tell me and I will explain more clearly.

once your at the top make sure to watch ALL of the ATEs possible then go to where quina was then you will find some kind of hole and jump down it with quina,get the treasure chest then go all the way back up.(sorry if this isnt very accurate because i havent done it and saw it in a guide.)

You have to watch all ATEs featuring Quina. Then at the screen left of Cleyra's entrance you'll find Quina distraught over not finding anything to eat. S/he will jump into the quicksand there, Zidane will follow, they'll both fall through Cleyra's Trunk and land in a place where the treasure chests can be opened.

Thanks a ton you guys. :D I've actually never gotten those treasure chest before, though every time I play through I see them.