It doesn't seem to matter WHERE I put them, their always sealed off completely.
I always get errors about how it isn't sealed off or how it isn't touching 2 sides or something similar. The only time it works is if I have a simple room for a map and the portal going in the middle, and even then only one works.
This is really pissing me off, I read up on them and as far as I know I'm doing it right.
Can someone list the requirements etc