Custom:button-card template

Configuration Frontend
1

I’m trying to create a button card template - the system keeps displaying button card template is missing. The button_card_templates: is in the ui-lovelace.yaml - in config file lovelace mode: storage - what am I missing ?

2

Suggest to ask similar questions in the dedicated button-card thread.

3

Hi there!
Need some help in translating a Jinja-Template for Custom Button:

{{(states['sensor.nippes_s_bahn_koln_to_koln_hbf'].attributes.connections[0].departure | as_datetime).strftime("%H:%M ")}}

Works well in the Developer Tools / Templates, but not in CBC …
What ist the right Syntax there?

Thanks!