Hi. I have a 2011 A4. I am trying to get the Sat Nav to run from SD card. I tried to copy it using the car system but kept getting failures. I therefore did the copy on my PC. I have checked all of the files are copied across. However when i put the SD card and try to run sat nav from it i just get something about the medium authentication being invalid. WHat is the best way to get the SD card working and how do i do it? Thanks peeps.