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When I try to load a custom map into  Garmin etrex Vista HCx I get an error that says (not exact wording, but close) "Map is 00 kbs, memory is 1789 mb....." and it wont load. I have a 2 gig card installed. I am confused as obviously I have the room, so why wont it load? I am using windows 7 and have the latest Mapsource version 6.16.3.