Last night we put in a sensor - waited approx. 45 minutes and attached the transmitter. It blinked green - and we thought we were in the 2hr warmup, when 30minutes later we get a Change Sensor Alarm, disconnected, reconnected - ISIG was 0 (zero). Left it in for several more hours, did another Start Sensor - and it took. ISIG was lower (under 10) for the first few hours, and is now sitting around a 12. The Sensor and BG's last night were spot on! 2 or 3 pt difference. I don't think I have EVER had an ISIG of zero before, maybe I never noticed. The whole thing just seems strange and is NOT an experience we have had before - just wondering what the rest of you think?