Great success experienced by Mahindra and Barndog.  So no common denominator yet.  Mine came from Cummins last year.  But some of my issues were:  1st time grafter, felt I may have over watered my resting grafts, found a few Jap grubs on roots of deceased rootstocks, used city water, healed in miracle-gro potting soil, fruit in same fridge as my stored scions.  Not sure if all or any of that mattered.  Goal is to get called up from the grafting tee-ball team to instructional league next week...