Check to see if both the HDMI end and the USB end of the adapter are connected correctly.
Make sure the HDMI end of the adapter is connected to the HDMI on your second display. Use the included HDMI extension cable if needed.
Make sure the USB end of the adapter is plugged into a USB power source. If the second display doesn't have a USB charging port, use the charging port on a device power supply or another USB charger.
For the most reliable connection, use a USB charging port that's directly connected to a wall outlet. Use a USB extension cord if you need more length for your USB connection.
Make sure the electrical outlet you're using is working properly. Test it by connecting something else.
Did that fix your problem?