I have 2 fire zones set up using System Sensor i3 series photoelectric smoke sensors. One zone is using two sensors in series (models 2WB) as a 2-wire zone with one 2.2kOhm EOL resistor. Other zone is one sensor (model 4WB) using as a 4-wire zone, also with one 2.2kOhm EOL resistor. Whenever I test these smoke detectors, I get a "fire trouble" alert and nothing can reset it except time, like one or two days and it goes away. Now, for the first time I got a "fire trouble" for the 4-wire zone after recycling power on the M1. Only way to get rid of the alert is time, about 2 days. What is wrong? Thanks!