Sorry, I was sleeping at the helm. Your LG GSA-4160B will not support Dual Layer burnning. I should have looked.
Have also update Cyberlink power producer, clone dvd 2, dvd shrink and nero, all without luck. The drive can read dual layers ok but it will not burn dvd-r dl. I have used it to burn dvd+r dual layer no problems.
By you stating that you burned dual layer+r's I was thinking in a different direction.