Ok I used FIU on this file and transferred it to the Nuvi 255 unit (still named as gmapprom.img). There are no other maps on the device. It doesnt say the map is locked but there were no cities, roads, or names for anything when I try to search. (type in something and nothing comes up)

I tried one last thing by taking the unlocked img and created mapsource files for it, like before, and sent it to the Nuvi (renamed the gmapsupp to gmapprom). Same thing as before...I get some street names but when I select a street there is no information for it (locations, house numbers, etc).

The Nuvi 255 I have should support NT maps like this so I'm not sure what's goin on....it should be showing results when I search a street name :S