Just bought a char to 80, defense skill won't level?

I tried letting low (5), mid (50), and higher (70+) mobs hit me for a while and my defense skill is still 1/400.

Weapon skills will go up when using them but defense skill ain't moving.

Any advice?

Turns out the mobs need to be green in order to level defense. Doesn't apply to weapons (can level on low level stuff).