OH3: Doorbird pressed rule not triggered


I have an instance of Openhab 3.1 and a Doorbird running on the same network. I succesfully connected the Doorbird via the Doorbird Binding to Openhab (Doorbird - Bindings | openHAB).

When I now press the Doorbell Button, I can also see the following entry in the event.log file:

2021-10-06 14:29:39.546 [INFO ] [openhab.event.ChannelTriggeredEvent ] - doorbird:d210x:doorbell:doorbell triggered PRESSED

The problem which I am currently facing is that the folowing rule which shall ring the bell is not triggered (it is more ore less what is documented on the binding page linked above)

rule "Doorbell Button Pressed"
    Channel "doorbird:d210x:doorbell:doorbell" triggered PRESSED

Do you have an idea what could be wrong ?

Thanks for your support!

Make sure your xxx.rules file loads without error (recorded in your openhab.log)
Make sure your rule “name” is unique.

As this is my first rule, I only have 1 *.rules file. It is also loaded properly according to the openhab.log.

I created an item for ```
“Doorbell Button Pressed”

like in the Doorbird Doku and it works with when "Doorbell Button Pressed"received command on 
then xy.sendCommand(ON). It is very simple done with the main.ui.