You must learn a special skill to tame Lesser Dragonkin. It is taught by the tome, How to Train a Dragonkin. This may be purchased from Kaestrasz in Valdrakken at renown level 23 with the Valdrakken Accord.
Level scaling: Most NPCs will scale with the Hunter's level, within the constraints of their level range. Hunters can tame regular NPCs up to 2 levels higher than them, but can only tame elite NPCs of the hunter's level or below.