We are currently working on a project of coffee plants adaptation in Costa Rica, using CIRAS-1. We have been facing problems with using auto cuvette, as we are trying to record reads at different PAR levels to plot the light response curve (starting at 1000, and gradually decreasing with 100s difference). We are using the car battery to power the cuvette, which works perfectly, all the chemicals in CIRAS have been renewed and we tried changing settings (like Leaf Area from 2.5 to 4.5, temperature , etc.). Our CO2 is set to 440 and with differential CO2 stably falls to 400 ummol. As there is no CO2 fluctuation, we are messing our head why stomatal conductance tends to stay at 9999 , after several zero modes and differential balances.Any expert, who could give his opinion on this? Thank you !