I purchased a used Garmin Quest on Ebay. My computer connects to the quest and recognizes it, and I put in a valid unlock code (verified by Garmin's tech support). When I go to transfer maps using mapsource, Mapsource recognizes the unit, but it gives the message "Your GPS does not support map transfer" - keep in mind I have another quest hooked up to this computer that works perfectly. What to do? Is this a sign of a broken unit?