There are a few possibilities:
- Make sure your optional Epson serial interface card is set up properly.
See Setting the conditions for the model C823051 Serial Interface Card
See Setting the conditions for the model C823071 Serial Interface Card
- If you are using a straight through modem cable, change the cable to a null modem cable.
- If you are already using a null modem cable, ensure that the settings for the printer's serial port match the settings on your computer.
- There is always the possibility of a loose connection or a bad cable. Disconnect and reconnect the cable on the PC and the printer and try printing again. If you are still experiencing problems, try a different cable.
- The problem may be related to your computer's serial port. Try using the printer on another computer to determine whether that is the case.