I have been trying to export data from senitnel-2 to GeoTIFF format. Everytime after exportation I got a total black image with the same max & min for each bands, as shown in the screen shot below:screen shot of exported asset

This should be very simple but I just can't see where I did wrong, the image shows perfectly in the earth engine code editor.

here's my codes: https://code.earthengine.google.com/fcf59b29db565c73f262bddd2992f089