I think there are 2 different sets of stats used in Dragon City for breeding dragons as I have bred a volcano dragon 26 times and have not got a single flaming rock dragon BUT my friend has bred a flaming rock dragon 24 times and has not yet got a volcano dragon - it seems we are on different breeding paths so 1 player can easily breed 1 set of dragons but finds it hard breeding the other set

It has nothing to do with level but more to do with LUCK. Each player has a different dragon list of those that are easy to breed and those that are very difficult to breed.