To connect ND2730 to the computer, you need to power it up before the connection.
1. Power up ND2730.
2. You will see X-copy ready message on the LCD.
3. Then connect USB cable to ND2730.
4. You will see PC <-> USB on the LCD if it is USB connected.
Even if you see 'PC <-> USB' on the LCD but cannot connect, please check below link for the trouble shooting.
If you don't see ND2730 connected at the windows 'device manager' even if the LCD showing 'PC <->' USB, then that means possible USB cable error or USB connector error.