Connected Sectors

I'm working on a CTF map for something, and I'm having this problem where I make a sector, and when I highlight it with the sector tool, it thinks that it is the same as every other sector. If I try giving it properties, every other sector is changed also. Is there any way to stop this? It's getting REALLY annoying! I have the wad with the problem in it below.

http://www.mediafire.com/?ev7azi96pptzasw

There doesn't seem to be a Thok Barrier. Remember always start with one then add the stuff inside. You might have to restart your map too. :(

Hmm, that would do it? I thought you could do it in both orders, but I guess not...

Anyways, I figured out what the problem was. I had drawn one fourth of the symmetrical shape in the center and then copied and flipped for the rest of the parts. Apparently, Doom Builder doesn't like that...

Re-outline the sector you want to change.

Connected sectors overlap each other and may cause problems to the level.
Example: When you enter 3D mode on SRB2DB you may see holes in the floor.
If there is a vertex in a different sector that's already connected to another, move it away.