My skill and my mobs doesn't work

For resume, i make a very explosif mob with particule and cie but when i spawn this mob, he don't cast the skill
my mob it's a Zombie for info. here it's my skill :

BoomAttack:
Cooldown: 100
Skill:
- effect:explosion{amount=555;hSpread=4;speed=0;cooldown=100}
- damage{amount=12;cooldown=100;ignorearmour=true;}


And this is my mob:

Boomer:
Type: ZOMBIE
Display: '&cBoomer'
Health: 40
Damage: 5
Skills:
- skill{s=BoomAttack} @trigger ~onAttack >0 0.25
Equipment:...

My skill and my mobs doesn't work