Thank you all

Govert: I have tried both methods, connect the usd first then open program. Unplug usb then reboot then open program then connect usb. Still no connection.

otaku521: I tried 2 different usb cables. They are all able to transfer data.

Geezatec: I checked the "System setting" there is no such USB on/off. It seems the USB can't be select enable/disable.

One thing I want to know, should I connect the charger with 12v dc input for connecting pc?

Any idea, why this is not working? I have tried this charger in 3 different computers and still not able to connect.