@marcovitch
You might need to give more information as to what are you trying to do. Send a new primary detail map to region 49, i guess? If so, check the command used in the BATfile is in accordance Webupdater.exe and the *.img file [i.e. ensure the paths to locations and names are correct].

Also you need to be sure that the img file is not larger than the unit's available region size. If you don't know the actual size, dump the region using [Only registered and activated users can see links. ] to see what's available. That will also give you a backup of the existing map. Read from Page 3 onwards particularly Posts #34 & 35, they're regarding SP 27x0 and 26x0 but one of those methods should work for your GPSMAP 278. The current primary detail map in rgn49 [hex 31] will be dumped as a *.hex file and it will be larger than the actual image as the entire available space is dumped both used and unused so you'll then know if your intended img file will fit ok.