[mkgmap-dev] known issues with Garmin Montana?

Hi, are there known issues with mkgmap-generated maps and Garmin Montana? One of my mapusers has the following problem. My map of Germany is on SD-card. He can activate the map, but mapscreen stays blank (only gpx etc. is shown). But if the Montana is connected to the pc, the map will be shown correctly in BaseCamp. I have no problems using my maps with my Oregon, also no other user report a problem with other devices. Someone any guesses? Maps are found here: http://www.aighes.de/OSM/index.php Henning