Getting a Sonos speaker to come on in the morning

I have read some threads / Google’d it, but I can’t make it work …

I have this in my automations.yaml

# Morning Sonos
- alias: 'morning sonos'
    - platform: time
      at: "07:10:00"
    - service: script.kitchensonosmorning

And this is in my scripts.yaml

#Sonos Kitchen
  alias: 'Kitchen Sonos Morning Start'
    - service: media_player.turn_on
      entity_id: media_player.sonos_kitchen
    - service: media_player.select_source
        entity_id: media_player.sonos_kitchen
        source: "BBC Radio 4"

The Sonos speaker is called media_player.sonos_kitchen in the Developer Tools section, and BBC Radio 4 is the name of a “favourite” within the Sonos iOS app.

Where might I be going wrong? I’d also like to set a volume, but not sure how or where …

Many thanks!