How do I play the haunting song?

There is a piano. And there is a music box, which plays a little tune on loop. The game wants me to play the first 8 notes from that music box.

There is also this enemy hint: "si re si re si mi si mi". (That's B D B D B E B E for ya yanks.)

I've tried however all combinations of 8 notes that could match up these notes (such as ↑←↑←↑↓↑↓, ↑•↑•↑←↑←, ↓•↓•↓←↓←, etc.) and nothing happens. If I ignore what the monster says and just try to play what I hear, I get ↑↓↑↓•↓•↓ — but that also doesn't work, and neither do slight variations (•↑↓↑↓•↓•↓→). I'm not very good at all at matching notes with sounds, or notes with notes, but what the music box plays and what I'm playing don't sound quite unlike.

What gives?