I just got my 880 (very cool so far) but I'm having issues controlling my volume on my onkyo receiver. It works, however, one in 10 tries or so, it will inverse the volume controls temporarily. Here is an example of what happens when it goes bad:

I'll hold down the volume up button and it'll increase. Now, when I hold down the volume down button it'll start cranking it up even more as opposed to turning it down! I can wait a few seconds between volume up/down controls or do it instantly - won't matter. Once it's in this mode, it'll do this until i let go of the button again.

Really frustrating because i'll go to turn down the volume and it'll all of a sudden crank up super loud.

Either the codes in the database are bad for volume up/down for your particular device or you're not using the right device from the database OR you've got more than one command mapped to a single button.

I'd check all three and if you don't get the desired result then simply learn the volume up/down commands from the original remote.