Please note: From the factory, the LED control is in the off position. For most indoor lighting conditions, you will need to turn the LEDs on by rotating the grey light control wheel to see anything.
 

When you connect a Plugable USB2-MICRO-250X microscope to your system, the LED light will NOT turn on automatically.  You must manually launch Digital Viewer or another webcam software to use the microscope.  The LED will power on when the device is in use by an application.