OK, this glitch has been addressed many times. Its not full, but it says it is. Please fix this before anything else is added into the game. While farming the boss in Kensington park I died and quickly tried to port back to my friend at the last boss. Then it wasn't full, but one of my friends friend had ported in. Then I quickly logged off and ported back and it said full. :l
If somebody else teleported in, then there will be four wizards there (assuming there were four before you left), and you can't get in.
Confirmed.. although you said you ported in on a friend. Your friend probly had someone else port, on him. and that friend had someone port on them, etc.etc.