Skeletal Sniper Skill

I use the skill of the skeletal Sniper quite often, but sometimes (around 1 in 3 or 4), i trigger their poison arrow, i see the cost in mana paid, but no arrows sent.

It really is frustrating as i don't have much mana.

I don't know why they don't send their skill, but if they are out of range or if they cannot "see" the target, the mana shouldn't be spent...

Seconding this.

Want to note that your line of sight is what matters for whether or not the archers will fire the poison arrow, not theirs. So if you are trying to fire a poison arrow around a corner, but can't directly see the targetted location, it won't fire. Once I realized that, it helped me cut down on the number of null poison arrow firings.