probably cause you werent using it like WL_CHAINLIGHTNING_ATK since thats where its animation is
but if your talking about a new skill using the throw shuriken animation just as its own
you need to call BF_WEAPON and throw shuriken together in the skill.c ... that is, if you cant make it with skilleffectinfo in the data.grf
something like this
skill->attack(BF_WEAPON,src,src,bl,NJ_SYURIKEN,skill_lv,tick,flag);
then just make a bunch of different options in syuriken and you could link them to other skills possibly easily.... id have to find the proper call or whatever though... but ill post about it if you dont figure it out
because the animation itself is linked to the skill id