Hi artanis,
Firstly, are you running The Peasants Rebellion? (instead of The Shattered Kingdom)
Also, which patch are you using? Maybe if you're using an old patch then that could break it. What does it say in the top left of the main menu? If it isn't 1.58 SR2 then download that patch from here:
http://knights.x10hosting.com/KaM/Downl ... nglish.exe
Install it and try again. If it already says 1.58 SR2 then you don't need to.
Please don't take this the wrong way, I am just checking: The problem could be that you downloaded a dodgy illegal version of the net. If that is the case then I suggest you try to find a copy from somewhere else, because some of those versions are completely uncomatible. (someone else said the same thing and that was the problem)
Secondly, where did you get the campaign from? Maybe the version you downloaded is corrupt.
Try downloading this version: (unless this is the one you are using)
http://lewin.namsys.com.au/kam/missions/TheNewLands.zip
Then install it and try again. (if you originally downloaded it from my mission site then don't bother)
Are these the locations where you put the files?
KaM - TPR\mission\dmission1.dat
KaM - TPR\mission\dmaps\save01.map
Also, when it starts (before you lose) does it look something like
this? If it doesn't then it is probably to do with the map.
If none of those things fixed it then please let me know, and I try to help you further.

Maybe send me the mission file (.DAT) and I'll see if there is a problem with it. Use a website like
iFile.it to store it temporarily.
Best of luck,
Lewin.