First, please ensure that if you are using the front HDMI port that you are also using the front USB port marked “TOUCH”. If you are using the HDMI port on the rear of the unit you must also use the USB port on the rear of the unit marked “TOUCH”.
If your touch function is still not working and you are using a Windows OS then please go to Control Panel – Power Options – “Change plan settings” – “Change advanced power settings” – USB settings – USB selective suspend setting – change this to “Disabled”. Then go to Control Panel – Device Manager – Universal Serial Bus controllers – right click on every sub-heading in this category and select “Properties”, then click on the tab ‘Power Management’ and untick ‘Allow the computer to turn off this device to save power’. If you are using a Mac, upgrade or downgrade the system to Mac OS X Mavericks (10.9 – 10.9.5), connect the Mac to internet and it will recognize the touch screen within a few minutes.
If you have gone through these steps and your screen’s touch functionality is still not working or is working sporadically please try using a USB hub to boost the signal strength of your PCs USB port.