Beckhoff ADS

I added already my AMS route on my CP6706 to my raspberry pi
Next I added this code to my configuration.yaml

ads:
  - device: "192.168.86.51.1.1"
    port: 851

switch:
  - platform: ads
    adsvar: GVL_HomeAssistant.bDrukknop
    name: Drukknop

Why am I getting following error when I restart the server?