Blank tickets are almost always a paper problem, not a printer problem. These printers are thermal: they only print on one side of special heat-sensitive paper, with no ink involved.
Check two things:
1. Is it the right paper? Use the rolls we supply. Standard receipt paper from a supply store may look identical but won't work in these printers. Need more rolls? Text 518-255-7617 and we'll get you stocked.
2. Is the roll in the right way? Thermal paper only prints on one side. Open the lid and make sure the paper feeds from under the roll, up toward the front, so the printable side faces the print head. Quick test: scratch the paper with a fingernail. The printable side shows a dark mark.
Re-seat the roll, close the lid, and press feed. If a test print shows text, you're back. If it's still blank on the correct paper, restart the printer (unplug 30 seconds, plug back in) and text us if that doesn't clear it.