The temperature lock is likely on and set to an incorrect range. Use the button to unlock the temperature range. The lock/unlock button is the second button down on the left side of the image being viewed and is half red and half blue. When the lock is engaged there will be a blue vertical line on the left side of your camera view and a red vertical line on the right side of your camera view.
Note: Sometimes, the IR software will turn on with the temperature lock button engaged. This occurs because the temperature lock button was left on the last time the software was used.