You should invest in some temperature and humidity gauges to watch the levels you have in the tanks. You can find these at any local pet shop or online. The ideal heat/humidity for White's is up to 85f, sometimes 90f, and down to 70f at night, with a humidity at 65-75%. White's can handle a good amount of highs or lows in both of these areas, but keeping them ideal most of the time is best for their health. Right now I have been misting lightly in the morning right after I turn their lights on for bed and heavily at night after lights out to retain the rainy season type setting.

Try buying some gauges and getting a better control on your husbandry, and then see how they do. The best are obviously the digital ones, but those can be a bit pricey so I go with the liquid crystal strips for temperature (they just look like a piece of black sticky paper with squares and numbers along the sides) and a dial hygrometer for humidity, though these aren't always so accurate.

Hope this has helped!