My Time gui doesnot works?

print("Script Started")
script.Parent.Parent.Lighting.TimeOfDay = "24:00:00"
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:00 PM"
wait(1)
print("functionally")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:01 PM"
wait(1)
print("functionally")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:02 PM"
wait(1)
print("functionally1")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:03 PM"
wait(1)
print("functionally2")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:04 PM"
wait(1)
print("functionally3")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:05 PM"
wait(1)
print("functionally4")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:06 PM"
wait(1)
print("functionally5")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:07 PM"
wait(1)
print("functionally6")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:08 PM"
wait(1)
print("functionally7")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:09 PM"
wait(1)
print("functionally8")
script.Parent.Parent.StarterGui.GameTimeGui.Frame.TextLabel.Text = "12:10 PM"
print("functionally9")
script.Parent.Parent.Lighting.TimeOfDay = "00:30:00"

It is not working. The gui doesnot change. all other things works i tested with the print("functionally") text. what i do wrong?

My best advice is to just use a while true do loop and have it update the time, sorta like this...

secs = 0
mins = 0
hours = 6
gui = script.Parent.Parent.StarterGui.GameTimeGui

while true do
wait(1)
secs = secs + 1
if secs > 59 then
secs = 0
mins = mins + 1
end
if mins > 59 then
mins = 0
hours = hours + 1
end
gui.Frame.TextLabel.Text = (hour..":"..mins.." PM")
game.Lighting.TimeOfDay = (hour..":"..mins..":"..secs)
end

I'm still somewhat tired so I'm not sure if I got everything correct, however this should work.