Board Thread:Dragon City Gameplay Questions & Answers/@comment-26889659-20150827135216/@comment-779290-20150831151636

Make sure you breed the lower level Sanctury dragons before leveling up too far. If the Sanctuary is more than a couple  levels above the required level for the dragons you are trying to breed the odds of success start to go down. At Sancturary level 8, the chance of breeding Sanctury level 1 dragons is near zero.