There could be a few reasons why "ADD WATR" appears:
Appears when using pressure function:
The liquid level is too low. Add more liquid to the cooking pot to before restarting the pressure cook cycle. Make sure the pressure release valve is in the SEAL position during pressure cooking and that the silicone ring is installed correctly.
Appears when using steam function:
The liquid level is too low. Add more liquid to the unit for the function to continue.