Please see the following.

1. The error is showing because each heater temperature does not reach the printer setting
　 temperature. It performs printing operation within the ±2℃ range of the setting, thus wait
　 until the heater reaches the temperature. (The heater lamp turns green when it reaches the
　 setting). The orange light indicates that heating is in progress.

2. Check the heater lamp and if all of the lamps REAR (PRE), PRINT (PRT), POST (AFT) are not
　 lit up.
　 (Letters in ( ) indicates each name of the heater on the screen).

1) When you have lowered the setting of the heater temperature, there is a good chance that it
　 is waiting until the temperature is going down to the required by itself. If that is the case,
　 unload the media to help the heater to cool down sooner.
2) If operated in summer, environmental temperature may be higher than the setting.
　 (EX. The heater setting is 30℃, but the environmental temperature is 35℃, etc.)

　 It performs printing when the heater temperature falls into the ±2℃ of the temperature
　 setting, and you need to lower the environmental (external) temperature.
　 (Note that it takes a while for the printer to detect the external temperature 32℃ when the
　 room temperature is 32℃ and its temperature setting is 30℃).

　 If it is impossible for you to lower the environmental (room) temperature, then press the
　 [ENTER] key to start printing. If this is the case please double check your print quality
　 because it is out-of-spec operation in temperature.