Setting the core gui to false doesn't seem to do anything, how do I fix?

Let's put this straight forward, I put a script together setting the core gui. This is a local script in starter gui and looks like this:

local startergui = game:Getservice('StarterGui')
startergui:SetCoreGuiEnabled(Enum.CoreGuiType.PlayerList,false)
startergui:SetCoreGuiEnabled(Enum.CoreGuiType.Health,false)
startergui:SetCoreGuiEnabled(Enum.CoreGuiType.Backpack,false)

But it doesn't seem to be working, what should I do?

put the script in ReplicatedFirst, and do this:

local startergui = game:GetService('StarterGui')
repeat startergui:SetCoreGuiEnabled(Enum.CoreGuiType.PlayerList,false) wait(0.5) until startergui:GetCoreGuiEnabled(Enum.CoreGuiType.PlayerList) == false
repeat startergui:SetCoreGuiEnabled(Enum.CoreGuiType.Health,false) wait(0.5) until startergui:GetCoreGuiEnabled(Enum.CoreGuiType.Health) == false

repeat startergui:SetCoreGuiEnabled(Enum.CoreGuiType.Backpack,false) wait(0.5) until startergui:GetCoreGuiEnabled(Enum.CoreGuiType.Backpack) == false