I know it's not Aqua, because you'd have to be an idiot to not find chest 7 in Neverland if you've found chest 6.
So that leaves Terra and Ven. I'd guess Ven, except it just so happens that their 7th chest is in the same area. It's the one with a bunch of water you can swim in. You should already have the one in the little cave, so just explore that area.
As for Disney Town... that's just embarrassing D: Find the manhole in the main area near the save point. I'm sure all of your missing chests are in there.
For disney town, make sure you use thunder on the machine until it activates, then you go to a couple more areas. On the pinball, hit all the bumpers to unlock the middle. Also, there is a high ledge on the pinball machine that is hard to see. First land on the brown area then use first person mode and look to the left and up facing outward from where you are standing. You should see a ledge you can bounce to.
For Neverland, I'm gonna guess you missed the chest I couldn't find. In one of the areas, there is a chest behind a rock. If you find a chest spider, there should be a rock next to it. Let the cannonballs destroy the rock to find it.
ACCF: Name-Chris Town-Oblivion 1204-3349-5174 Pokemon Platinum: Chris 1677 0039 1771
daenym2164, I usually thank people who help but I won't be thanking you. You know why? Because you're just rude. I didn't ask for your help specifically so there was no need whatsoever to act all high and mighty.