Stucked at Home of Tricks

i can't reach the KEY. there is a word on wall it says "Turn on the Three and the fourth will be friendly". btw all levers in the dungeon is opened.
The forum for all Redshift games.
http://www.linux.redshift.hu/forums/
http://www.linux.redshift.hu/forums/viewtopic.php?f=24&t=6071