Right! (or wrong...)

I'm sure I am doing something wrong here...
-updated my nuvi 510
-used GarminExpress to create a backup (only a GPX file???) and wrote that to a SD card in my laptop
-copied the enture content of my Nuvi to the SD card as well (windows explorer, copy all)
-fired up WEBUPDATER.EXE
-it recognises the card as if it is the Nuvi510
-select Western Europa, write to C: disc on PC (Programdata/Garmin/Maps)
-it gets *****ing, downloading for about 1 hour and then it says it failed to update the maps.
-The folder is empty...


If you have a fix (and the time..), much appreciated!!!