I have followed the directions explicitly and the POI Loader program indicates, for example, "2 entries successfully uploaded" [or similar language]. However, when I try to search on the Nuvi for the new POI's, they just can not be found. Have tried using the "near different city" feature, "spell" feature, etc, under the POI menu, but no luck.
When you download the POI file (in GPX) format, also download a .bmp file of the symbol of POI file you're downloading - to the same folder, with the same file name as the gpx file just a different extension - ie: dowload timhortonscanada.gpx (poi file) and the timhortonscanada.bmp symbol file. As long as they're in the same folder the poiloader will do the rest. then it will be located in the extras like the others said.