Use Denon Code 811 for the primary main zone set. There are 2 additional code sets for the new series but you will need to add 2 additional recvrs to your programming to use them. They are codes 812 and 813. 811 is a solid proven code set. IF that does not work then you have a problem with your 850.
CEDIA Certified Installer and Designer. Denon CI, URC, Crestron