The 3D Buildings and Lane Assistant is not working on Garmin Mobile
The gmap3d.img is placed in the Garmin Folder on ur nuvi, the jcv file must be in garmin\jcv.
If you have 2 3D Buildings files, rename one of them to gmap3d1.img, should be also recognized


Just place the correct gmap3d.img in the same folder where u have ur gmapsupp.img.
But 3D Buildings are only working in nuvi7x5 series