Ok, here comes the laughter...

I came into possession of a bunch of these in Cyro doing Pve stuff, so thought I'd try defending a keep.
I utilise whichever the instructions says will work against whatever I'm shooting at.
I watch others fire thiers, and did the little tutorial of course with green lines etc, yet when I setup I can aim, but there is never an actioning "shot" or damage sequence from mine, yet the condition of my apparatus drops.
Green line goes red, but no shot flies, no explosion, etc.
Now what I missing? It's a stupid question I accept but I am truly perplexed.
II Swindy II
Australian on Xbox NA (ex EU)