It is possible that the chip on one of the cartridges makes little or no contact with the electrical contacts in the printer.
The cartridge holder needs to be placed in the replacement position. To do this, press the Ink / OK button on the printer to print or follow the step-by-step instructions in your printer maintenance menu.
Lift the flap over the cartridges and push the cartridge firmly in place with your hands. If this fails, lift the cartridge gently. Then firmly replace the cartridge back into position to ensure the chip makes proper contact with the connection points inside the printer.