Enter one note, hear another.

I'm having an issue with MuseScore: i have a whole host of instruments in my score. among them is a flute and a tuba. they both are listed as being two flats(im using the concert pitch setting) and when i play a b flat on the tuba and timpani, the note i hear is different than other instruments of the same key, except treble instead of bass.

The attached file is the problem file.

Thanks,
Josh