My script w'ont recognize a gui in a PlayerGui ?

game.Players.PlayerAdded:Connect(function(plr)
    local gui = plr.PlayerGui
    plr.CharacterAdded:connect(function(char)
        char:WaitForChild("Humanoid").died:Connect(function()
            print(plr.Name.." / Dead : true")
            game.workspace.DiedSound:Play()
            gui.DeadScreen.TextDead.Visible = true -- the problem is here
        end)
    end)
end)

when i try and i kill my character the output say that DeadScreen is not a valid member of PlayerGui