i'm stuck on the last will and testament - The Glabados Ruins.

i've killed all the monsters and i've inspected all the little statues on the left (and right) but the final gate just won't open. and according to every walk through i've read to try and find out what the hell i'm doing wrong, i'm apparently doing nothing wrong!!

anyone playing this game?? is there anyone who can tell me what the hell i'm doing wrong, cause it's really gettin on my nerves. i've a feeling it's something real simple and i'm just blind!