I'm new to tablets, etc. Forgive if question naive. . . I have a Yarvik TAB462 (10-inch tablet) in order to use MobileSheets app to display music scores. When I try to load the scores as .pdf files in the prescribed way, I'm told there is no path to the sdcard. Using Terminal Emulator to look at the directory, it shows the sdcard as 'permission denied'. How can I get the sdcard operating so I can load my music files?