Structure does not keep my saved data after reloading panel

Best Kirby forum members,

I’ve got my page broken down to this, i guess, the minimum amount for column, section and structure on a panel.

title: menu blok

options:
    url: false
    duplicate: false


columns:
    left:
        width: 1/2
        sections:
            left-top:
                type: fields
                fields:
                    item-name:
                        label: product
                        type: structure
                        fields:
                            product:
                                label: Productnaam
                                type: text

When i save some data in the structure and reload the panel, the data is gone. Does this blueprint look like it should work?

You cannot use dashes in yaml files, use underscores or camel case.