These were set around January 2010 ,while the same medium was used , pine bark and scoria ,  3 had Mycorrhizae added and 1 had Spagnum moss placed around the section directly under the cut the others had spagnum placed at the base of the pots  .I believe this is why it may have failed to root . The others had sharps around the cut area whereas the failed layer didn’t .The sharps obviously work by severing the callous and producing roots , the moss retains possibly too much moisture and the callous merely sucks up the moisture . Iwill re-set a series of new layers using the same methods to try to determine which is the best, most responsive method . The watering regeme for all the layers was daily unless rain was present , as the medium was free draining to allow good air flow .The spagnum moss may have inhibited the air flow around the cut also . Plenty of Questions too be answered ,  only another trial will shed light on some of these issues . Cheers Alpineart