Map: Height Maps

[Tomas]

I'm bit stuck with my map. I've used the tool and have a perfect heighmap. But whenever I try to place certain terrain to a hex the height of the hex will change as follows:

- if placing clear terrain and height was 0 it will be 5
- if placing trees and height was 0 it will be 0
- if placing pavement and height was 0 it will be 5
- if placing paved road and height was 0 it will be 0

- if placing clear terrain and height was 10 it will be 11
- if placing trees and height was 10 it will be 10
- if placing pavement and height was 10 it will be 5
- if placing paved road and height was 10 will be 10

In conclusion - placing almost anything besides trees or road ruins the height.

I've attached the heightmap so you can see yourself.

What can be done about that ?