Did you place dungeon hearts for the players and chose the wrong players for them? It's like the message says you must place from 1 to 4, not e.g. 1, 3, 4 and miss 2. If you have a two player map, then place 1 and 2, not 1 and 4 or so.
I used before units for player 1 and 2 and 3 but i saw that creatures after test were fighting between them after a while because i didnt add a dungeon heart for each of these units then i changed them all in empire and after that i get that message,i really dont know what to do :/
Yes I can understand that this troubles you and I hope I can help you by taking a look at your map. Can you please upload your test map file here?
You can find further information to where your file is located here: Saved Maps