If the printer prints vouchers but does not print receipts, continue with the instructions here.
Make sure the USB cable is securely connected in both the printer and the tablet, and that the cable is connected properly. You can try disconnecting and reconnecting the cable.
Make sure the USB cable is connected to the USB-OTG socket on the tablet. The printer may not work properly in the other USB sockets.
It can also be a defective cable and therefore needs to be replaced / a new one purchased.
If problems persist after purchasing a new cable and testing it, contact customer support by email email@example.com or call +420 602 405 047.