Umkas buried tresure map help!!!

[Metroplex]

I'm currently on my third play-through of KB:AP as a Paladin and yet I've never managed to finish this quest, the reason being I simply can't find the treasure!!!
I stand reasonably near the areas marked on the map, none of those lines that tell you to dig for treasure ever appear along these areas, so this quest remains unsolved.
Anyone completed it???
Can you help me, maybe I'm doing something wrong.
p.s. I have the map.

p.s.2: You know in Demonia, in the cave, there is a caged enemy, I was wondering if it is possible to free them and kill them? (Where you have to get the vampire head quest.)
p.s.3: Why is Demonis referred to as 'Demonia' as the place 'Bill Gilbert' visited when he beat Archdemon Baal the first time? A mistake by the developers???
Thanks a lot.