I have an invoice-table with a product-portal. The products (here "ads in a magazine") have a date (printing date). As an invoice can have n products I need (in my case) the lowest (earliest) date of all products to use this in the invoice.
If I place a summary field in the portal-table "products" with "minimim" on "date" I can integrte that field in the invoice-layout. But - now my problem - I cannot use this field (as it is a summary field) as a date with selector etc. It just shows the date. I tried to have a date-field in the invoice-table and -layout (like "lowest_date_from_booked_products") and a formula to just get the value form the summary-field but now data is displayed.
What do I wrong pr how should I do it differently? Thanks, Luna