I just reinstall Ubuntu 14.04 to my Lenovo G400s.
The laptop has a built in webcam as /dev/video0.
When I run cheese, no problem and it is showing what is the webcam seeing, but when I run guvcview, it just pop out a black screen. It show nothing no matter how I change the setting in guvcview.
What is the cause of this problem and how should I solve it?