I tried again this weekend and got it to work. The camera needs to wait the same duration as the exposure before starting the next exposure with lenr on. So 120s exposure, you need a 120s pause for lenr to remove the dark frame. Then you immediately begin the next exposure. This worked like a dream and because I was using a 135mm lens I did not need to autoguide and be tethered to a laptop, I manually dithered every 10 subs and ran lenr at iso 800, almost no noise shooting the iris nebula in mag 21.4 skies. Cant go wrong.