Basic configuration of my restful sensor

Configuration
1

Hi,
I want to configure my first RESTful sensor in homeassistant and are facing the problem that the sensor is shown as unknown after restarting homeassistant
Here is what I did in the configuration.yaml:

sensor:
  - platform: rest
    resource: https://tibber.com/de/api/lookup/price-overview?postalCode=69123
    name: tibber_energy_sensor
    value_template: "{{ value_json.energy }}"

What am I missing?

EDIT: SOLVED please ignore the question

2

So it will be empty, you have to wait for polling or populate it.