[ gpsdrive ] Problem using own map

[Brin Cooke]

I have gpsdrive under Xandros Linux. At the same GPS position I have  
downloaded 2 maps and both appear satisfactory with the current GPS  
position at the map centre. I added my own map which has a centre a  
few hundred metres from the current GPS position but on this map the  
current position is shown (incorrectly) at about the map centre; as  
though it was a downloaded map! Any advice/help please?