OH2 Denon Binding Zone 2 Volume UP goform/formiPhoneAppDirect.xml?Z2UP

I have the problem that the command Z2UP (Zone 2 Volume UP) does not work with my Denon binding.
I tried the link dirket.
(http://192.168.178.49/goform/formiPhoneAppDirect.xml?Z2UP)
Then the volume of the second zone is turned up.

Can someone help me or is someone using the command Z2UP