Make a folder inside your mission folder named sound.....or is that sounds....I can never remember.
Anyway, place your sound file in that and then make sure the path in your description.ext points to the correct place.
sound[] = {"\sound\C02r01.ogg", db, 1.0};
or perhaps its
sound[] = {"\sounds\C02r01.ogg", db, 1.0};
Like I said I can never remember.
Planck