I moved your post over to Adventure Game Hints.
I see that the walkthrough at GameBoomers says this:
Go back to the guest room and the piano. Look closely at the sheet of music and see at the top: A=la, B=ti, C=do, D=re, E=mi, F=fa, G=so. Look down at the keyboard and starting with the first active key on the left, numbered 1 – 7, left to right, click on 5 – 6 – 7 - 3. It spells out GABE. If you have done it right the picture above the piano will move back exposing the missing jewels.
Perhaps your keys are numbered incorrectly?
Maybe another player can help you out here.