Unable to get Spotify to Chromecast working

Hi,

I quite a newbie regarding Home Assistant but I am getting there slowly. I am working on a Spotify to Chromecast (audio) integration, but can’t get it to work. I have tried the following in development tools (after putting it in a script all the time).

{
  "media_content_type": "playlist", "media_content_id": "spotify:user:111133445:playlist:6fq24kYOoWcLRamoTn3Lt4", "entity_id": "media_player.woonkamer_audio"
}

I noticed that the stream to the Chromecast seems to be initiated, cast starts and immediately stops. Haven’t found any errors until now and don’t know how to continue with this?

Help is very welcome