How do you manipulate Gui with Filtering Enabled on?

I read online that you have to use a remote event but it doesn't work. This script is supposed to make the button clicked turn blue when clicked. It works when filtering enabled is off.

script:

   script.RemoteEvent.OnServerEvent:connect(function(player)

local gui = player.PlayerGui.ScreenGuimain.ScrollingFrame.ImageButton1

gui.BackgroundColor3 = Color3.new(0,0,255)

    end

    end)

local script:

   script.Parent.MouseButton1Down:connect(function()
   script.Parent.Gui1.RemoteEvent:FireServer()

   end)