OK, what I did:
I check in the hidden file system and find a JCV folder from my original map(coming with my nuvi) thus I check if real intersection works and it works with the former map.
So the problem I suppose is the compatibility of the JCV file and the map you select in the system, I notice also that the original JCV file had a ".sum" file , what is the purpose of this file ?
Where can I find the compatible JCV file for the map 2010.20?
Thx for helping