I may not be understanding your problem fully, as I don't do much of this sort of work. I guess you should clarify what you mean by "normal map" though. Is this a texture you created and then UV mapped in C3d? I agree with what Frank asked. Where did this material come from?
If it's a procedural material, does baking the material in C3d not work for what you need? I've never had a texture map (diffuse) ever having a problem importing into another 3d app. I've even had a procedural metal in C3d come through in Modo without changing anything. Usually procedural materials don't work across different apps, unless they're built to do so. I have no idea how that worked, but it did.
If you post an image or sample scene of what you are having a problem with, someone that does this here may be able to help you better.