How could I brighten my model in game lightnig?

The upper building is my model:


This model was composed by 2 warcraft models,
the bottom is doodad Cathedral, and the top is a campaign tower,
I used Geosetmerger to merge them, and repainted the skins.

Now the problem is, we can see the part of Cathedral is too dark in game.
(At the same time, the tower looks ok as human barrack in game.)

I have mago's model editor, Oinkerwinkle's all tools. Wordpad of course.
How could I fix it?

(I know one way is to make the materials unshaded,
but it looks bad, too. I just want the building's lighting looks like our barrack.)

I suspect it's Olof Moleman you want to be talking to about this; what you have there are dodgy normals, and I hear you can fix that in Vertex Modifier -- though I wouldn't have a clue how to go about it myself.

I didn't know why but the model showed normally
after turning it 180 degrees.

Thanks a lot.