An error I dont understand?? Not Valid Member Of ScreenGui?

I have a script. and when ever I do a test it says Open is not a valid member of screen gui. When it clearly is.. heres the script.

local button = script.Parent.Open.TextButton
local upgrade = script.Parent.Upgrade
local player = game.Players.LocalPlayer
local frame = script.Parent.Open
local close = script.Parent.Upgrade.Close
local Floor = script.Parent.Upgrade.Floor
local Time = script.Parent.Time
local Material = script.Parent.Material
local CM = script.Parent.Upgrade.ChangeMaterial
local close1 = script.Parent.Material.Close
local fabric = script.Parent.Material.Fabric
local wannabuy = script.Parent.WannaBuy
local MP = workspace.MainPlat
local CFM = script.Parent.Material.Floor

button.MouseButton1Click:connect(function()
    upgrade:TweenPosition(UDim2.new(0.01, 0, 0.13, 0), "In", "Quad", 1,true)
    frame:tweenPosition(UDim2.new(-0.1, 0, 0.94, 0), "In", "Quad", 1,true)
end)

close.MouseButton1Click:connect(function()
    upgrade:TweenPosition(UDim2.new(-0.1, 0, 0.13, 0), "In", "Quad", 1,true)
    frame:TweenPosition(UDim2.new(0.01, 0, 0.94, 0), "In", "Quad", 1,true)
end)

local text = Time.TextLabel
local platform1 = workspace.Platform1
local platform2 = workspace.Platform2
local platform3 = workspace.Platform3
local platform4 = workspace.Platform4
local platform5 = workspace.Platform5
local platform6 = workspace.Platform6
local platform7 = workspace.Platform7
local platform8 = workspace.Platform8
local platform9 = workspace.Platform9
local platform10 = workspace.Platform10
local platform11 = workspace.Platform11
local platform12 = workspace.Platform12
local platform13 = workspace.Platform13
local platform14 = workspace.Platform14
local platform15 = workspace.Platform15
local platform16 = workspace.Platform16

Floor.MouseButton1Click:connect(function()
    game.Players.LocalPlayer.leaderstats.Players.Value = game.Players.LocalPlayer.leaderstats.Players.Value - 1
    Floor.Visible = false
    Time.Visible = true
    text.Text = "5"
    wait(1)
    text.Text = "4"
    wait(1)
    text.Text = "3"
    wait(1)
    text.Text = "2"
    wait(1)
    text.Text = "1"
    wait(1)
    text.Text = "Upgrading.."
    wait(5)
    local part = Instance.new("Part")
    part.Parent = game.Workspace
    part.Name = "MyLittleUpgrade"
    wait(1)
    platform1.Transparency = 0
    wait(2)
    platform2.Transparency = 0
    wait(2)
    platform3.Transparency = 0
    wait(2)
    platform4.Transparency = 0
    wait(2)
    platform5.Transparency = 0
    wait(2)
    platform6.Transparency = 0
    wait(2)
    platform7.Transparency = 0
    wait(2)
    platform8.Transparency = 0
    wait(2)
    platform9.Transparency = 0
    wait(2)
    platform10.Transparency = 0
    wait(2)
    platform11.Transparency = 0
    wait(2)
    platform12.Transparency = 0
    wait(2)
    platform13.Transparency = 0
    wait(2)
    platform14.Transparency = 0
    wait(2)
    platform15.Transparency = 0
    wait(2)
    platform16.Transparency = 0
    wait(1)
    MP.Transparency = 0
    wait()
    platform1.Transparency = 1
    wait()
    platform2.Transparency = 1
    wait()
    platform3.Transparency = 1
    wait()
    platform4.Transparency = 1
    wait()
    platform5.Transparency = 1
    wait()
    platform6.Transparency = 1
    wait()
    platform7.Transparency = 1
    wait()
    platform8.Transparency = 1
    wait()
    platform9.Transparency = 1
    wait()
    platform10.Transparency = 1
    wait()
    platform11.Transparency = 1
    wait()
    platform12.Transparency = 1
    wait()
    platform13.Transparency = 1
    wait()
    platform14.Transparency = 1
    wait()
    platform15.Transparency = 1
    wait()
    platform16.Transparency = 1
    wait()
    Time.Visible = false
    CM.Visible = true
end)

CFM.MouseButton1Click:connect(function()
    CFM.Visible = false
    fabric.Visible = true
end)

CM.MouseButton1Click:connect(function()
    CM.Visible = false
    Material:TweenPosition(UDim2.new(0.12, 0, 0.13, 0), "In", "Quad", 1,true)
end)

close1.MouseButton1Click:connect(function()
    CM.Visible = true
    Material:TweenPosition(UDim2.new(-0.1, 0, 0.13, 0), "Out", "Quad", 1,true)
end)

fabric.MouseButton1Click:connect(function()
    wannabuy.Visible = true
    wannabuy.Yes.MouseButton1Click:connect(function()
        wannabuy.Visible = false
        MP.Material = "Fabric"
        fabric.Visible = false
        player.leaderstats.Players.Value = player.leaderstats.Players.Value - 1
    end)
    wannabuy.No.MouseButton1Click:connect(function()
        wannabuy.Visible = false
    end)
end)