PIP won’t read.

Hello! I work for St Joes peds/ neo team. We’ve been having an issue with our PIP reading intermittently. It’ll read the peep and sounds like it’s giving breaths while powered on but wont read a PIP. Do you have any suggestions? We’ve had our biomed look at it and they sent us a loaner but the loaner has done it as well. It’ll work normally then do it again. It’s happened at the bedside twice with two different vents. Thank you so much!