Yamaha DGX640 - Harmony Function?

I'm still working through exploring all of the functions of my new Yamaha DGX640. Everything is working as explained in the accompanying DVD except the "Harmony" button. Frankly, I don't detect any difference in sound between this button being on or not. But in the DVD video (http://www.youtube.com/watch?v=OwQ-6ujYlnw) there is a distinct difference. (Note that "Harmony" IS lit in the LCD when it's on.)

However, when I activate the "Dual" button next to the "Harmony button, I DO hear two voices.

Is there something I'm omitting when trying out this feature? Perhaps another setting somewhere that needs to be activated/de-activated or adjusted?

Any help with a step-by-step procedure to get this to work would be greatly appreciated! Thanks.

Bert

Well, I have the 620, and when I press it, nothin happens either. Not much help am I?

Perhaps not. But at least I'm not alone then in understanding how it's supposed to work! 8-)

Thanks.

IIRC you must be using the accompaniment feature for the harmony to work. Is that what you're doing?

AHA! That was the missing piece of the puzzle!

Thanks!

And it will harmonise the melody differently if you play different chords.