I tried your solution and you were right!! I unzipped with 7-zip using windows and now the sd 16gb is recognized by my wipnav!!!
Some little info for mac users:
-unzip with 7-zip in windows (win is virtualized in virtual box);
-sd 16gb formatted fat23 in OS X with disk utility;
-in OS X just drug & drop the folder "database" previously unzipped in windows.
The first time my wipnav did't recognized the sd. Just take off the sd and reinsert it ad it works!
Thank you very much!!