“Heroes of Might and Magic V: Tribes of the East”

Hello everyone! Please help: in the game Heroes of Might and Magic 5: Tribes of the East, some cities lack the third upgrade for certain creatures. For example, in the Dungeon castle, all units can be upgraded to all three levels, but for dragons, only Twilight Dragons are available. Even if I build the building for Black and Red Dragons, they don't appear in the recruitment slots. And in the Haven castle, the third upgrade is only available for Peasants – all other units can only be upgraded to the second level! Could it be that I need to install a mod? Thanks in advance!