What I was trying to do was get one step out of the way so you didn't have to come back to it. Instead I just confused the heck out of you. SORRY.
The '3 light door' was the best way I knew to describe it, not that you had to put the light in each spot. There was just a space for three balls of light. That's all. When you encounter the door only one light is lit. If you snag that one light then you can take it over to the gate and get the hat. If you don't want to do that step because it isn't part of getting the stupid door open, don't. Just leave the light where it is and move on to step five. It's important to remember that the deluminator can only hold one ball of light at a time. By the time you get to the middle island your deluminator has to be 'empty' so you can pick up the light there. You don't want to light the middle light. You want to take the middle light.
See if its clearer now.
I might suggest just restarting the level (hit the home button down until it says exit. You will gain all the money, and objects you have acquired.)
If you restart the level I think if you follow my instructions minus step 4 you should get the door open to move on. You can always pick up the hat in the free play version.
I will shorten my instructions to pertain just to getting through the door.
1) lumos- Walk through the glowing bubble and it will light everything.
2) move to the slight out cropping near the chest that needs to be dug up
3) raise the first stone. (I suggest you let it sink back down and do it again before jumping. It gives you a better idea of the speed at which you need to move.)
4) Jump to the first stone and immediately start to raise the second. DON'T WAIT OR RAISE IT ALL THE WAY.
5) Jump and then IMMEDIATELY jump to the middle.
6) Take the light in the middle.
7) Repeat 3,4 & 5.
8) Use the light to open the red wall
9) cut the circle and build the Apparation point.
10) Take back the light & Apparate away.
11) Put the light in the missing space- which removes the gate at the top.
12) Remove the light to the right- this will cause a handle to appear on the bottom step.
13) drag each step out. Jump up to parseltounge puzzle and solve it.
14) Leviate the apparation point over the water. (It guides itself...and if you do it wrong it floats back. Just try again if necessary.)
15) Get in the apparition point that you arrived in. This time it will show you a wheel. Use your thumb control to keep it on the right side arrow. Apparate.
16) Take the light you are carrying to the 3 light door, putting it in one open spot. Apparate back.
17) Take the second light.
18) Repeat step 15 then put the last light in. The door opens.
19) Walk in.
If that isn't any clearer I'm sorry. I've written it the way my brain thinks.