antonag07, how did you place creatures from Haven into the Dwarf Castle? I will disable the reproduction of neutral creatures due to week effects. Start the mission from the beginning; when loading a saved game, say from version 1.3-4, all information remains the same in version 1.6. This is possible in campaigns where you can start with a saved game after updating the map, but here, with each update, you need to start the mission from the beginning.

P.S. The only explanation for why you can't complete it is that in version 1.2-1.3, the system by which the hero moved was buggy, and in those versions, heroes really did stop wherever they wanted (not only when moving to the Dwarves but also to others). Most likely, you started playing on an early version of the map and then continued playing on new versions with information from the old version...

Added 4 minutes ago
Update 19.03.2012 v.1.7

Week effects for creatures have been disabled.