Tabs inside user blueprint

Hey, maybe I didn’t find it in a guide, but is it possible to use tabs in user blueprints? This is my Blueprint.

title: Kunde

tabs:
  kontoKundendaten:
    label: Kundendaten
    sections:
      fields:
        type: fields
        fields:
          vorname:
            label: Vorname
            type: text
            width: 1/2

Should work, what exactly does not work as expected?

Is this the whole code? Because if so, Kirby only displays tabs if there are at least 2 defined.

Thanks for the help, it works now. I had a tab wrong.