CR Volume via Generic remote

Hi all!

I’m trying to get my Maschine master knob control the Control Room Volume knob.
I am sending a controller message which is getting in fine, and controls other functions,
so it is working.
But if I select the “Command/Control Room” Category, there is no entry for CR volume.
In fact, all entries seem to be “On/Off” type, there are no variable entries…

Anyone throw some light??

Best regards
Andy