I built a wood drying kiln 4’ x 4’ x 16”. Using a dehumidifier, a box fan, a 250 w heat lamp, with 219 Board feet of green white oak. Cut about 2” thick. Started at 45-50 MC and 72 F got up to 93.5 F and 93.5% RH by end of the third day. Dehumidifier is set to 55% which I was planning on lowering down to 40% as the moisture content lowered. By the morning of day 4 the RH reads 82.5 an hour later 71.4. What’s going on here?