Sonos, selecting a source to play (port) to a target (another port)

Configuration
1

I have many Sonos device and I want to have a script sending my computer source that goes out to a Sonos Port (line in) to another Sonos Port (line out with active speakers).

The final idea is to link buttons to volume up, volume down, computer source port to port, and play/pause. Got the first two working.

For now I am stuck to this (it does nothing):

alias: New Script
sequence:
  - service: media_player.select_source
    data:
      source: media_player.sonos_desk_computer
    target:
      device_id: media_player.unnamed_room_2
mode: single