google search says "It is very easy to overheat the eggs in still-air incubators and difficult to maintain proper humidity. During the warm-up period, the temperature should be adjusted to hold a constant 101°F for still air, 99°- 100°F for forced air."
Now, since you're sure she was sitting for three weeks, those eggs should be very close to "lock down" (don't turn them). Did you candle them to determine if they're still viable after their momma died? Do you know how long they were without their mother's warmth?