Welcome to the forum. I think most of the responses you will receive will be helpful...not flaming posts, unless you refuse to take the advice that's given

Last 10 days is no big deal. How often are you feeding? Once a week should be sufficient.

How big of a rodent are you offering? and are you offering mice or rats? Have you tried both?

To raise your humidity, try a damp towel on top of the enclosure each day. Or mist with a spray bottle.

Do you have a digital thermometer? or those analog stick ons that you get from petco? Those are complete junk. You can get a good Acu-rite at Wal-mart (in the section usually near light bulbs and stuff...usually the outdoor home stuff) The Acu-Rites have a probe for "outdoor temps", but you put it on the warm side, so the unit will read the cool side and the probe will read the warm side...

For your under tank heater, I would suggest you look into Spyder Robotics and get one of their thermostats. A cheaper alternative would be a Ranco