I don't have a problem measuring HPA, but recently I have not been able to Crony Co2. I have a Beta model. I mostly shoot indoors under florescent lighting. I always use the factory light kit. It seems to work fine using HPA, but when I try to measure Co2 velocities from 12 g cartridges I always get errors. I am not firing full auto, and backed away so the cloud would not be measured. Any thoughts?