Distinct group of images in two blue-print sections

Hi, I want to build a blueprint for distinct groups of images, one section to only one main image, and another to an image gallery without a specific limit. I don’t want that the image put in the first group (main image) also appears in the gallery (details). I want separate those groups. So I have coded this blueprint:

  - width: 1/3
        type: fields
            label: Main Image
            type: files
            layout: cards
            headline: Details
            type: files

Good, but I’ve selected and upload images, saved them, and gone to the dashboard. When I returned to see my page, the main image is not there. What happens?


No dashes in field names!

Thanks! I put mainimage and now works!