It sounds to me like you don't have a good seal, so the ambient air is circulating with incubator air, so all the water is escaping from your incubator into your room. Also don't use a fan in the incubator as this dries them out too--as well as promoting more air to escape the incubator, as it is now blowing the air "out" of any cracks in the incubator. Developing eggs need very little fresh air. In fact, I put as many as 80 cornsnake eggs in a small plastic box that couldn't possible hold a clutch of ball eggs. A clutch of ball eggs in a much larger box surely doesn't need supplemental air, since that box has a larger lid with more area for more air to "leak" in. I put mine in plastic shoe boxes with NO airholes, and check them about once ever one to two weeks.--until they get close to hatching, then I check more often because I can't help it!
Taking the lid off once every two weeks doesn't hurt them at all, and the air that "leaks" in past the top is plenty of oxygen for them.
Another problem I often see is people using bottom heat. I don't know what your incubator is like--I've seen some very poory designed home made units. But bottom heat will cause this problem as well. (kind of like slowly boiling all the water out of a pot that sits on the stove.) While this will temporarily raise the humidity of the air, it will dry out the medium and the eggs as well.
Rodney