I do not know how it is unable to operate, but here is what it is supposed to do.
An invisible brick in the workspace has a script inside of it that will make it visible at 18:00:00, but it will not work, I have a fair feeling that the day/night script in the workspace is preventing it from operating, but here is the script.
if game.Lighting.ClockTime == 18 then script.Parent.Transparency = 0 elseif game.Lighting.ClockTime == 8 then script.Parent.Transparency = 1 end
Simple script, although I cannot come up with any solutions.
You should be checking every time the clocktime changes using GetPropertyChangedSignal, in which case, the script should look something like:
Lighting:GetPropertyChangedSignal("ClockTime"):Connect(function() -- "ClockTime" can be exchanged for any property and this function exists for any object with a property. if ClockTime == time then elseif then end end)