Technical issues in Heroes IV.

Thank you very much for the advice. The map loaded, but without heroes (there were supposed to be two level 20 heroes with artifacts). There are two options left: either these heroes will appear later in the scenario, or I will play with new heroes (I'm glad there's a tavern in the castle). I figured it out. You don't need to touch the checkboxes, but the field specifying which campaign to transfer the heroes from was not filled in. I entered the name of the first map in this field, and everything started working perfectly with my old, leveled-up heroes. Kvant, thank you so much for pointing me in the right direction! :)