Current questions and answers regarding the map editor.

Hello, I wanted to create my own map in Heroes 5. The editor itself is in English. But the problem is that when I save it, it doesn't appear in the game. And when I open it again through the same editor, an error message pops up. Once, I just placed some monsters (neutrals), only 2 units, and it immediately disappeared from the list. Can you explain what I might be doing wrong when saving, or if I need to change something in the settings?