NHF – new heroes for Heroes V 3.1.

Yes, other mods for version 3.1 used to work perfectly, but yours doesn't.

Other mods are often more universal and work with version 3.0 as well, because they don't require support for scripts from version 3.1. But this one does.

Please, write the version of the .exe file. You can just hover over it - a tooltip will appear.

Added 6 minutes later
There are also different versions of the game 3.1: one from Buky, another from 1C. But I doubt that this affects anything.

Added 1 minute later
And yes: what hero was chosen initially?