OK, you can try for looking structure with using some ove linux distributon, or other way, you can uplod it on this way, using DOS command
C:\Garmin\WebUpdater\WebUpdater.exe /upload_file RGN=49 path=C:\garmin\gmapprom.img -autorun usb /unlock_check fid=2204 pid = 1 /i
2204 is ID of CN NT 2011, you'll need garmin tool webupated installed on your machine
[Please Register or Login to download file] And don't forget to rename your img file in to GMAPPROM.IMG cause this is a PRIMARY file, and if you send GMAPSUPP it will not overwrite existing gmapprom.img file which you sent it before on your device, and then is problem with that error, probably low disk space!
YOu can try with these 2 tools for sending img files to garmin devices...
[Please Register or Login to download file] [Please Register or Login to download file] p.s.
to test this thing, make smaller .img file with mapsource, about 50 mb, install before garmin mobile pc, and send that file to gamin mobile pc, unlock that generated .img file, renam to gmapprom.img, and after that, using dos command , that 50 mb file try to send to your device, just to check is there problem with disk space! What's capacity of internal hdd of your device - 2GB ?