JD,
Last year I propagated 3 Blk. Madeiras, all rooted easily for me. My brother managed to kill them when I was out of town (over-watered them). They were 5 months old.
IMO, 1) Blk M. does not like direct sunlight for the first year.
2) It's a slow grower (at least it mines were), even with half strength liquid fertilizer, given ONLY once a week.
So, Just be patient and give it some time.
Navid.