Distance from barcode
Make sure the barcode is close to the camera, and the camera video stream isn't blurry.
You may need to slowly move the item to and from the camera in order for it to focus.
Low resolution
Webcams typically have a lower resolution than the average smartphone camera, meaning a lower scan success rate. If this is the case,
you may need to try a different webcam, or use a smartphone instead.
Fixed position
If your camera does work and it isn't in a fixed position,
it may be worth resting the webcam on the tabletop so you do not have to repeatedly reach the games to the top of your screen just to scan.
Chilloutgames