Set Chromecast with Google TV Volume

I have a chromecast with GTV that I am using to cast music to.
The volume is set to be controlled via Chromecast.
The Chromecast is connected to a Moukey receiver via bluetooth.
I control the volume on the chromecast either through the google home app or if I am casting from Youtube Music, from there.

I currently have automation that is controlling volume on another smart speaker (JBL with Google Assistant built in).

I added the same code for the Chromecast, but it is not working for the Chromecast. Any idea how to set the volume?

`service: media_player.volume_set
data:
  volume_level: 0.15
target:
  entity_id: media_player.pool_radio`

This started working. Not sure what I did differently.