What to do if the display show the "file not found"?
1. Check the format of the USB driver. Make sure it is FAT32.
2. Make sure that you are not using the old X-Sign designer format to play with the X-Sign player v1.5 or later.
3. You can just rename the filename extension from xxx.bdp to xxx.sbdp on Windows OS.
(Click the right button of mouse on the file then choose the "rename" function on the function bar.)