[DECtalk] dectalk express, software volume control?

[Patrick Perdue]

Hi:
Does anyone know why the commands for changing volume aren't working on
my dectalk express? I've tried sending the commands straight, as well as
through jaws and supernova, and nothing does much, other than of course
the physical thumbwheel on the unit itself.
Is this an issue with my specific unit, a firmware issue with version 4.2CD, or do they all do this?
Why have a software controlable volume when it does nothing?