For starters, you have posted the receiver that you have. As Buzz suggested, is there a set of commands that the protocol supports that you are lacking?
With regard to Denon Integration, have you had an opportunity to see this thread? I took some time several years back to compare/contrast the various modules available at the time.[Link: remotecentral.com]
And for those who might be wondering, this is not a plug to sale/license my module. I have not been licensing the module for the past 3 years.
I recently purchased a Marantz Preamp which BTW is now using the Denon Control Protocol (Woohoo!). I actually pulled up the source code for the first time in over 3 years.
Integration was fairly simple and almost drop-in. I was able to pretty much maintain backward compatibility with only very minor enhancements required.
For current users, I may offer a minor update but I see nothing on the horizon at this time.