i'm stuck in Lunacy (Gekkamugentan Torico)

how do i get through the room with the music boxes in the city of moons where you can use the wind-up key?

there is only one full walkthrough for this game, but it doesn't really help here:

"R,F,save game, use the wind up key on one of the boxes and press back. if nothing happens, reset the game (ABC + START) and load up your save game and try a different box. when you get the key, use it on the locked door in that room."

that doesn't work for me, or am i just too stupid?
i did it ! but i did it like in the summer and i cant remember correctly, but i think in the city of moons there is place were u jump off the clif while falling u hear a song from nowhere, thats the melody that ui have to do to the music box , well i think first go there fall off, than go back save it, and do what the walkthrough tells u to do,