Can't use delay skill

Hello,
I have a problem with my actual configuration.
The "delay" skill always worked for me until some days when i've tried to configure a new mob.
I'll give you my configuration:

Mob:

Skelor1:
Type: WITHER_SKELETON
Display: '&6Skelor'
Health: 50
Damage: 8
DamageModifiers:
- FIRE 0
- LAVA 0
Skills:
- message{cooldown=20;m="<mob.name><&co> Vous pensez avoir une quelconque chance, mortel ?"} @PlayersInRadius{r=40} ~onCombat >0 0.2
- message{m="<mob.name><&co>...

Can't use delay skill