The sensor is located on the remote, so if the remote is positioned a few shelves higher the base a lower reading would be normal until there has been sufficient time of the cabinet being closed for the humidity to travel upward. However, if the remote is on a lower shelf and or the humidity does not rise to Set Point even after a few hours of the humidor being completely closed, please check the following: The water base has water, but is not more than 3/4 full. There should be about 1 inch of space between the fill level and vents so the humidity can properly escape. The unit is properly positioned so the vents are facing an area where the air can travel straight up uninterrupted by any boxes or obstacles. The seal on the humidor is tight and Auxiliary Fans may be necessary.