What's a 291-90? It's not on the Xantech web site.

Try a couple of other codes to see if perhaps there's just something weird with this command.

Oh, the Zune remote can output Denon commands that work?

Try learning any code twice, carefully holding the button down the same amount of time, and compare the codes. You might have toggle codes, although with toggle codes you would get confusing sometime operation but no repeat operation.

That's all I can think of for this.

Thanks for posting in the installer's forum and here, and putting a note over there about it. Less confusion is good about where a thread is.