What wrong with this?

while true do
wait(0.05)

if script.Parent.Parent.Control.Value == 0.03 then
while true do
script.Parent.a.SurfaceGui.TextLabel.Text = "This train Terminus here."
script.Parent.b.SurfaceGui.TextLabel.Text = "You can exit this train"
wait(5)
script.Parent.a.SurfaceGui.TextLabel.Text = "or stay here"
script.Parent.b.SurfaceGui.TextLabel.Text = ""
wait(5)

if script.Parent.Parent.Control.Value == 0.05 then
script.Parent.a.SurfaceGui.TextLabel.Text = "Ad.test"
script.Parent.b.SurfaceGui.TextLabel.Text = "Ad.test"


end
end
end
end

This script not is full staple Wrong:The script do no to anything! Value:Number Value l need a fixed script

while wait() do
	if script.Parent.Parent.Control.Value == 0.03 then
		script.Parent.a.SurfaceGui.TextLabel.Text = "This train Terminus here."
		script.Parent.b.SurfaceGui.TextLabel.Text = "You can exit this train"
		wait(5)
		script.Parent.a.SurfaceGui.TextLabel.Text = "or stay here"
		script.Parent.b.SurfaceGui.TextLabel.Text = ""
		wait(5)		
		if script.Parent.Parent.Control.Value == 0.05 then
			script.Parent.a.SurfaceGui.TextLabel.Text = "Ad.test"
			script.Parent.b.SurfaceGui.TextLabel.Text = "Ad.test"
		end
	end
end

Try this and then if it dosent work, tell me what the output is and I can edit it.