Problems opening maps on my GPS HELP !!! Leaving for big trip in days

Hi I am pretty new to Openstreetmap but I followed the user guide that is provided.
I have sucessfully highlighted the tiles I need, built the map, got the email and followed the link. I made sure I had Mapsource installed on the computer and that its not running. I then downloaded the file and ran it. It is visible when I go into mapsource under osm routable, I then highllighted each section and click send to device and it says its sent. This part all seems to work exactly as it should but when I turn on my GPS which is a Garmin Zumo 660 I cannot seem to get the maps up, if I go into tools, settings, map, map info it says its there. There is the usual CN Europe NT and OSM map Kazakhstan and Russia which is what I downloaded. But if I go into where to, address, change country I cannot select anything except the preinstalled European countries. I have tried turning the device off and on again as suggested but it still wont work.
Anyone got any suggestions as we are leaving for a big trip in a few days and I am tearing my hair out.
Any help gratefully received