This is a problem that I've been experiencing here and there over the past 4 days of playing around with the DNA200 but just this evening I've been practically pulling my hair out trying to get it working. Sometimes I'll be in Temp Control mode and instead of showing me the temperature when I'm firing, the temp field will turn into "---F" and just fire it like a kanthal coil. I've been able to fix it previously by tightening my screws or resetting my atty, though I did have to rebuild once a couple days ago to get the DNA200 to recognize my ni200 coil as such. Over the last couple hours I've put 4 different builds in my atty and tried them and all of them did the "---F" thing when firing. They were all built with either 26 or 28 awg ni200, the two different gauges are from two different brands btw, all are spaced coils. I tried tightening the connection, loosening the connection just a hair, resetting the atty by unscrewing, letting it cool, putting it back on, still "---F" when I fire it. I've tried changing the temperature and trying again, still no luck. I got frustrated and set it down, then I just came back to it and now it is working fine. I'm sorry I can't provide any more information but this is what is happening.