Hi Sir, 

Have you used any rooting hormones? Or any other root promoting treatments? 

Season of harvesting and propagation of vegetative material, diameter and position of branch cuttings and also the age of tree itself play an important role in rooting of vegetative propagules.

additionally we must have to see

(1) whether the cuttings are susceptible to fungal infections

(2) composition of media

(3) position of planting

(4) influence of external environmental conditions e.g. sunlight, humidity, watering interval etc.

Be remember that the potential of success of branch cuttings always differs from tree to tree.

Best !