Dear Tom1807, Dear Catymag,

I bought my GPS Nüvi 255-White in France, but now I'm living in Turkey.
I dowmloaded files and unlocked turkish map in mapsource.
When I transfered the map in my device, it came originally with "gmapsupp" name. But when I switched-on my GPS I received the message error "Can't Unlock Maps".
So I didn't see the turkish map appearing in "Map Info" in my device (still only the CN Europe NT 2010.10 original one) and precision of turkish map is still as original one also => only highway are showned !
I tried by renaming the file as "gmapprom1" => same message, still no map appearing, same low precision.
Then as "gmapsup2" & "gmapoem" => message desappeared, but still no turkish map in Map Info, and still original low precision !!

In my Nuvi 255, I noticed that for all original files I have (gmapbmap, gmapprom, gmaptz), there's a second file with same name and ".sum" extension ... should I need a similar one for the turkish map file also, to be recognized by my device ? How I can get it ? Or do I need a specific name that were not mentioned in that forum for a Nuvi 255 ?

Thanks in advance for your kind support if you have a solution.
Regards