The only other thing might have been to bleach it, to kill the bad organisms. But some cuttings also just aren't meant to root, regardless of the TLC.

Have you tried Rootone, a rooting hormone?

If the soil you used is from your ground maybe use new potting mix in place of soil that may be contaminated with fungi and other nasty bugs?

Sue

Thanks John and Sue, it just breaks my heart to see cuttings die or even when trees in my orchard reach the end of the road! (Sigh)

-jbs

I know your pain. Trust me. Also, rooting hormone, esp. powder types tend to promote rotting in fig cuttings per USDA/UC Davis and experience.