First off, make sure you feed the plant well and wait about an hour or a bit more, so your cuts will be well hydrated. Try to take cuts from as low on the plant as possible ( more mature) and when you cut, quickly dip in water and then a rooting hormone of some kind and then get them under a humidity dome and mist a few times a day for the first week ( they have to drink from the leaves for several days before the roots start)
I have had 100% success with the last 4 batches of clones going this route.
They have got to be kept a little warm, but they really need to be under a dome for a few days so they can drink up from the higher humidity. After 5 days, I start to take the dome of for a couple of hours each day. By the end of 8 days or so, they can start to be fed nutes again, They were eating about 650-700ppm when I took them, so I start with at least 400-500ppm of nutes after that and in a few more days, they can start eating what they were eating when you took them.
Peace and Great Cloning
Asmallvoice