Basic map modding question

I've been trying to make some very basic changes to the campaign map to get an idea of how it all works however so far all my changes have either not done anything or caused the game to stop working.

First I tried creating a small square patch of water next to London. I drew a square of blue on the map_heights.tga and also a square of red in exactly the same place on the map_ground_types.tga (saving backups of both these files with Original placed infront of their names). I then deleted the map.rvm file. When I ran M2TW and started a campaign as the English the only change was that the ford near london was now a bridge, no lake was present.

Thinking that this might be that I hadn't made changes to the other map files I decided to try something different. I opened every single map and flipped them through 180 degrees (saving backups as above). This caused the game to crash as soon as the campaign was loaded. This didn't wholey suprise me as the text file that places the various cities would no longer correlate with the maps.

Finally I tried making the maps all complately land with no sea or height variations. This also resulted in the game crashing when I loaded the campaign map as in the above situation.

I was hoping someone could tell me what I'd done wrong or even better give me a brief tutorial on how to change basic features of the campaign map e.g. adding land or sea.

Thanks in advance.

Tom

No one got any help?

And didnt you place that lake on mountains or any resource?

That could be it yeah. Certainly that would explain my the map didn't work with the other modifications.

However it would be useful if someone could post a list of files needed to be modded for the campaign map.