@kraid: I’m sure you’re right.
I could not get the VertexNormalTool to work. I spent a day figuring out how to export properly and in the end decided to use 3ds Max and don’t need to worry 
Also I found out that you get texturing errors, when your uv islands are located far away from the center of your map or scaled really big.
In these cases you need to set a higher tiling value in your texture maps and scale back the uv islands.