I have cloned quite a few with all but one being successful. I used some rooting gel, although, you could probably have success with out it.
Justin I had similar problems when I first started using the plant. I guess as I had changed many things over time I could not tell you exactly what the differance was but I believe in my case the biggest differance was the extra lighting.
One observation I do have is that the large ones I have bought seem to never quite develop the bark. At least not the ones I have kept indoors 24/7. I wonder if they have over grown them through chemical means and the substandard indoor condtions do not allow them to develop it as well. Not being subjected to wind could also do this as this forces them to develop stronger structures in order to survive. With the small ones I have bought, clones and ones that get in rotation outdoors they get quite thick sturdy bark throughout the sturcture. This is what you are trying to achieve....well at least I am. They are very, very strong.
Maybe when it warms up you can get a rotation going sticking some outdoors. The addition of the extra lighting did stabilize mine enough to where I did not have to do this but I still do. Maybe you could throw up some additional fluorescents, with some new plants and still be able to salvage them when spring comes around.
