The code you have goes to the GPSr your using, meaning when you got you unlock codes from the garmin site you used that code on the GPSr you are trying to load the maps onto. If they are, uninstall Mapsource and all the other mapsource utilities and reinstall them then go through the wizard and unlock maps with the GPSr hooked up.

When you go tho the Garmin site and use your coupon code to access your account, is your GPSr listed??