I need help with a health billboard gui ?

So the script below was supposed to lower the hpBar when the player takes damage, i used print to see if that part even runs when i change the hp of the hum, but it does not run at all, what is the error ?

game.Players.PlayerAdded:Connect(function(player)
    player.CharacterAdded:Connect(function(character)
        local HPBar = game.ServerStorage:WaitForChild("BillboardGui").RedBar.Bar
        local hum = character:WaitForChild("Humanoid")
        local clone = game.ServerStorage:WaitForChild("BillboardGui"):Clone()
        clone.Parent = character.Head
        hum:GetPropertyChangedSignal("Health"):Connect(function()
            local hp = hum.Health/hum.MaxHealth
            print("ya mother")
        end)
    end)
end)