Thanks for your answer, yes, looked like I installed the wrong dir, I meant to use the NTU version. But this shouldn't change too much in this case I think.

I also have the gmap3d.img file, but thought this contains only the 3D buildings and not 3D surfaces? But I would use it if I knew how to integrate it into Mapsource/Basecamp. In the Thread you linked I could only find informations regarding installation on the device.