I had the same issue, so I send a message to the commercial support and they sent me a new one.
You should be careful when you plug the reader into the usb port:
-is the sd card fully inserted in the reader ? When I say fully i mean it.
-is the reader fully inserted in the usb port ? Same here
Also, don't be scared of waiting 4-5 minutes, sometimes it takes time to read the card.