Why doesn't Filter Enabled let me open up a GUI?

I am making an RPG. But my problem is that my GUI doesn't work anymore.

There is this server script, which is supposed to open up a GUI when you talk to a NPC.

But it's now broken because of Filter Enabled.

Here is the script.

script.Parent.DialogChoiceSelected:connect(function(player,dialog)
 local gui = script.Parent.ScreenGui
 if dialog.Name=="Choice1" then
  gui:Clone().Parent = player.PlayerGui
 end
end)

I have asked this question many times, but no one can't seem to answer it. But if you can, please just fix this script and explain why this server script isn't working.

Instead of cloning a gui into PlayerGui like that you should do.

gui.Enabled = true

Also you must use a local script to access things in PlayerGui so a remote event may be helpful. http://wiki.roblox.com/index.php?title=Remote_Functions_%26_Events