I have been downloading photos to my Samsung Galaxy Tab 10.1 for a couple of years and have downloaded hundreds from SD camera cards through USB connector without an problems. Last week a downloaded fine and then a couple of days later it wouldn't work. It recognised the USB connector but came up with a message "Blank USB Storage". I've tried it with two different SD cards both of which work fine in both cameras and there seems no problem with the cards. Why has it suddenly stopped working?