OK. I don't know why I am having so much trouble with this!! Here is what I did: - Put 1/2 cup salt and 1/4 water in coffee cup, mixed it up well. - Put the coffee cup and the entire thermostat/hydrometer (including probe - but did not put the probe in the salt water mixture) in a ziploc bag and sealed it. - Waited 15 hours - temp is 79.9, humidity is 43% What am I doing wrong? Isn't the humidity supposed to be about 75%? There is no way that it is off by 30%!