MeshId Can't assign id from a table by pressing a button Error??

repeat wait() until game.Players.LocalPlayer.Character

local p = game.Players.LocalPlayer
local cd = game.StarterGui:WaitForChild("CustomizationData")
local l = script.Parent.Left
local r = script.Parent.Right
local chat = p.Character:WaitForChild('Hair') -- Created Hair Accessory with a MeshPart(Handle Inside it)
local hn = script.Parent.HNumber
local hid = {522589968,520462259}

local count = 0

function Update()
    chat:WaitForChild('Handle').MeshId = "rbxassetid://"..hid[count] -- It's supposed to insert the id from the table but it doesnt works
    hn.Text = count
end

r.MouseButton1Down:Connect(function()
    if count >= #hid then
    else
        count = count + 1
        Update()
    end
end)

l.MouseButton1Down:Connect(function()
    if count > 1 then
        count = count - 1
        Update()
    end
end)

Anyway I tried making the Hair or Hat Customization and then comes up an error says

Unable to assign property MeshId. Script write access is restricted ? what does that means .. why I can't change the id of an MeshPart from the localscript