Strange black fog (possible spoilers)

[n0ir]

At the very end of the game !!
Cannot enter the third teleporter (stairs). I tried clicking on the fog itself, on the area behind, on the edge, used WASD mode, and nothing happens. It's like an invisible wall. I really need a script... please help me.
My version is fully patched+MotB+SoZ

Sorry, my english sucks xD

[swcarter]

Are you sure you're at the right fog? We show a map of the area here.

SWC

[baron667]

better walk into the fog rather than trying out random scripts.