http://projectpokemon.org/forums/showthread.php?5532-List-of-46h-and-47h-values-of-HG-SS-locations
Are you making sure to set the location to "Faraway Place"? If you do, then Pokemon HGSS automatically knows to look at 46h/47h Hex Values. That way, if it gets traded to D/P/Pt, it will just say "Faraway Place" instead of the Johto location, because D/P/Pt don't read 46h/47h values.