Assuming the built in cameras are the issue,
\are you using the provided software ?
You can try to update the ROM and / or drivers for those devices.
sometimes an update may not install properly and re-updating the ROM and / or specific device drivers would solve the issue
Attached is a link for the English device manual:
If you are having difficulties with the device recognizing an attached camera device, you may need to go to camera device manufacturer website and download the appropriate drivers to match your tablet device operating system and connection type.
Ex: USB driver for camera connecting using a usb port connection. Also ... confirm proper cable is being used.
Ex: Some connections require 5 contact point cables, others only 4 contacts - this will be determined by your devices.
I hope this was helpful.