When asking for technical help at the very least let us know the version of firmware you are running.Cliff's Calibration (Mapping) Guide is a MUST READ: http://www.vemssupport.com/forum/index.php/topic,97.0.html
That's alright, unless your calibration value is way off. Normally 150-220. What's yours?
So, it's off then and no good.Is the sensor hot after a few minutes of leaving the calibration on?It could simply be a fluke, but values should be in the range 150-220 to hit 20.9% (+/- 0.5).