Reason①: Your labels are loaded in upside down

Please ensure your labels are properly loaded. The print side is facing up. See the image below:

Reason②: Ensure your labels are "Direct Thermal" labels.
 

Reason③: Try to print out test page

Press and hold the Feed Button while turn the power ON, until you see the red and blue light flashing at the same time, then release the Feed Button.

Or watch this video：