BenQ 9H.F6GPK.NA4 Installation Handbook page 74

Strong light reflection.
The interactive software
(purchased and installed separately
by user) may not be compatible
with the system.
Poor USB connection.
74 Troubleshooting
Re-direct the lights or move the display to another location
to avoid unwanted reflections from light sources.
• Try with a different version of interactive software.
• Try with the basic drawing program pre-installed on your
computer. (e.g. Microsoft Paint in Windows).
Check if the USB cable has been connected properly, or
try with another USB cable.