Hi, I'm new to this community, I'm encountering an error while using Agilent E4412A power sensor while performing zero/cal using E4419A power meter. While Zero/Cal power meter throws a error( CAL ERROR chB). I have checked the Power meter channel B performance with another Power sensor and CH B is fine. I suspect the Power sensor. When internal ref was applied to the sensor it reads -21.45 dBm instead of 0 dBm. What could be the possible problem causing this error in the power sensor.