Do I need a remote event to show a GUI?

Trying to make a quest GUI that opens when you click something.

script.Parent.MouseClick:Connect(function()
	game.Players.LocalPlayer.PlayerGui.QuestGUI.Frame.Visible = true
end)

I have that in a local script but nothing happens when I click it. Do I need to use remote events just to change the visibility of a GUI? I also tried it in a non-local script and it said that the GUI was nil even though it was not.

Can anyone enlightenment in how I'm supposed to do this?

EDIT: I did not know that you are using a ClickDetector. Whoops!

While ClickDetectors can work using local scripts, it is not a good idea to put local scripts in the detectors because the scripts can only work if it is a descendant of a Player (e.g. put it in a Gui, or StarterPlayerScripts so that the scripts inside can be copied to the Player's PlayerScripts and run).

Here is the code, which will be in a local script that is located in StarterPlayerScripts:

local detector = workspace.HixBox:WaitForChild("ClickDetector") -- Where is the ClickDetector located in?
detector.MouseClick:Connect(function()
	game.Players.LocalPlayer.PlayerGui.QuestGUI.Frame.Visible = true
end)

If you have any questions, feel free to put them in the comments. I hope this will work.