Siri/HomeKit turn up/down commands

Hi,
I’m trying to control air conditioning temperature and TV volume with Siri. I want to say something like “turn up the tv volume” (“sube el volumen de la tele” in Spanish). I don’t want to say “set the tv volume to xx”.
Is it possible? How can I do it?
I’ve tried with this item:

Dimmer VolumenTeleDimmerSiri "Volumen de la tele" [ "Lighting" ]

But when I say “turn up the tv volume” or “turn down the tv volume” (“sube el volumen de la tele” or “baja el volumen de la tele” in Spanish), instead of getting INCERASE and DECREASE commands on the dimmer, I’m getting alternatively ON and OFF commands on it, no matter which of the two I say. For example, if say “turn up” three times I get ON, OFF, ON.
Anyone knows how to do it?
Thanks.