Micro climate Thermostate problems magic eye day and night cycle

I have some micro climate thermosates with the "magic eye" for lite. to sence day and night.  now that it is darker my tanks only heat up a few hours a day.  there is a small screw at the bottle of the thermostate that is for the sensor sensitivity.  if you turn it clockwise it should be day time all th time.  however, min dont work... i thought it was broken.. but i have 2  and they both do the same thing,... a

anyone have any experience with a micro climate thermosate