to kenta2: I formated SD card and did all things again, but no luck. Still my device couldnīt find the maps.
to catymag: file extension is img, that is also checked.
I red from other post that HomePort can use the maps even they are locked. I think that Garmin has invented new copy protection system? This 3.00 firmware update which I have in my 720 is from october 2010, if that helps.