NCF – Extended list of Neutral creatures.

When I try to launch the mod, it says that the original version of Heroes 5 was not found. Does anyone know how to fix this?

Does it display any other messages? Usually, error windows appear first, and then this message.

Added 5 minutes later
The first thing that comes to mind is the "Dark Champions of the Necropolis" mod (Death Knights on dragons). This mod is based on a creature from NCF, and there is some leftover data that breaks the NCF.