Wierd colors on retextured vanilla models

[J.Heinrichs]

Hello Guys

I’m trying to model some new fortification models for a mod. To save time, I wanted to use some fragments of the vanilla models. As you can see on the screenshot, weird coloured polygons appear, when testing the stuff ingame.



The parts of the model that I build up from scratch are showing up right, but the ones that I haven’t torched, except from assigning a new texture to them, look quite weird. Has anyone got a tip what I have to bear in mind before I export the model, to avoid this?