Increase Volume by specific amount google speakers

Configuration
1

I am able to set the volume on my speakers no problem.
The issue is increasing or decreasing by a specific amount.
The goal is to control volume on a specific set of speakers with a Google Chromecast.
I use Google assistant, it calls a scene which runs a script.
I can’t get the increase or decrease to work.

What I have right now.

service: media_player.volume_set
target:
entity_id: media_player.pool_radio
data_template:
volume_level: “{{ states.media_player.pool_radio + 10 }}”

2

service: media_player.volume_set
entity_id: media_player.bathroom
data_template:
volume_level: “{{ state_attr(‘media_player.bathroom’, ‘volume_level’) | float + 0.05 }}”

Tried that but got this error.

Executed: June 11, 2023 at 6:55:10 PM
Error: Error rendering data template: ValueError: Template error: float got invalid input ‘None’ when rendering template ‘{{ state_attr(‘media_player.pool_radio’, ‘volume_level’) | float + 0.10 }}’ but no default was specified