InfoPath Dev

Dear Hilray, First of all, I would like to express my thanks for your help. It seems that your version really works. I was able to publish that. But when I edit or just open the filter and try to save again, I get the error message. I suppose, the problem is related somehow to the software I use. Maybe I will try another (e. g. English) ...

Sure. Here you are! The form is in Hungarian. BUT! I could save the form only if I made date field (DÁTUM) equal to starting date (KEZDŐDÁTUM), but it is not appropriate for me. I marked yellow the calculated value.

I have many SharePoint lists, and I have one "report" form. On this form I have calculated values which count items of lists (with filter, e. g. item's date is between starting end ending dates given on the form) All calculated values work fine, except one. When I create a filter for date (iterm's date >= starting date) I get ...