A. Red light is an indication that NT-LP110A has a problem with your label. Most likely, the printer needs to re-identify your label.
Please ensure there are multiple labels available to the printer and then run the automatic label identification. Simply press and hold the top button on NT-LP110A until you hear one beep. The printer will then feed labels back and forth to learn the gap and other properties of your labels.
If automatic label identification does not work or red light remain, please turn off the printer by using the power switch on the back and turn the unit back on.