Why is my frame not opening when button is clicked?

I put a button (local Button) on a brick and its supposed to open a frame (Frame) on the screen when pressed (and vise versa, if its already open) All the objects are present in the Workspace and the frame (Frame) is already preset to not visible.

local Button = script.Parent.SurfaceGui.Change.ChangeButton
    Frame = script.Parent.Parent.RollingChair.Seat.ScreenGui.Frame.Visible
    function onClick()
          if Frame.Visible == false then
            Frame.Visible = true
        elseif Frame.Visible == true then
       Frame.Visible = false
        end
    end
    Button.MouseButton1Click:connect(onClick)

Note: You must be sitting in the Seat in order to see the frame on the ScreenGui.

When I'm sitting on the seat and press the button (local Button), the frame on the ScreenGui does not become visible.

(Below is the script in the seat to activate the ScreenGui that contains the frame.

a = script.Parent.ScreenGui
function onChildAdded(child)
if child.Name == "SeatWeld" then
if child.Part1.Name == "HumanoidRootPart" then
local player = game.Players:GetPlayerFromCharacter(child.Part1.Parent)
if player ~= nil then
a.Parent = player.PlayerGui
a.Bus.Value = script.Parent.Parent.Parent
end
end
end
end

function onChildRemoved(child)
if child.Name == "SeatWeld" then
if a ~= nil then
a.Parent = script.Parent
end
end
end

script.Parent.ChildAdded:connect(onChildAdded)
script.Parent.ChildRemoved:connect(onChildRemoved)