Note that the Music Database is designed to select voices and styles which are supposed to be good choices for specific songs-- although the song names used in the Music Database entries are somewhat disguised.
But as far as your question, selecting one of the Music Database entries will most likely select some other voice instead of a piano sound.
If you want to use a piano voice instead of the default voice for a given Music Database entry, select the desired Music Database entry first, then select Voice 1.