Thanks, Mike! The problem here is caused by `mate-volume-control-applet` file location. It came from `mate-media`, you are right about this package Problem persists even with the installed `mate-media` package. In Debian 10 (buster) it was located in PATH - `/usr/bin/mate-volume-control-applet` (see https://packages.debian.org/search?suite=buster&arch=any&mode=path&searchon=contents&keywords=mate-volume-control-applet ). But in Debian 11 and newer it is located in non-PATH place - `/usr/libexec/mate-volume-control-applet` (see https://packages.debian.org/search?suite=bullseye&arch=any&mode=path&searchon=contents&keywords=mate-volume-control-applet). So it can't be found by `mate-tweak` (see https://sources.debian.org/src/mate-tweak/22.10.0-2/mate-tweak/?hl=78#L571 ).
My local quick and dirty hack is the following: ``` sudo ln -sf /usr/libexec/mate-volume-control-applet /usr/local/bin/mate-volume-control-applet ``` But I would suggest fixing this problem in the `mate-tweak` script - for example you can call this applet by full path - `/usr/libexec/mate-volume-control-applet`. It is still applicable for default Debian installation without Ayatana indicators.
