Lovelace mini-graph-card doesn't show graphic

I have installed mini-graph-cards through HACS, then put some code in Lovelace:

      - type: 'custom:mini-graph-card'
        entities:
          - sensor.my_val
        line_width: 5
        font_size: 100
        hours_to_show: 24
        update_interval: 3
        hour24: true
        name: Изменение Температуры на улице за 24 часа
        show:
          extrema: true
          labels: true
          name: true
          state: true

It shows digital value and name, but graphics are empty.
Can some body help me with it?