Multiple targets in data field

In yaml i would use the following:

media_target:
  - media_player.kantoor
  - media_player.woonkamer

Now i want to trigger the same script from node red but i am unable to pass to correct data.
Currently it looks like:

{"variables": 

    {
    "file_to_play": "/local/misc/deurbel1.mp3", 
    "media_target": [
        "media_player.kantoor",
        "media_player.woonkamer"
    ],    
    "media_volume":"50",
    "volume_non_playing":"50"
    }
}

But Home assistant is unable to pickup those values.

Hopefully someone can help