This may sound stupid, buta re you actually aiming directly at someone? I find that there has to be a target realitvely close to you and within your view in order to go into V.A.T.S.
If and when you get to Megaton, that would be good place to practice, because the if you target people they won't go hostile as long as you don't shoot.
Also, some more pictures.
My first duel against a minigun wielding dude.
I ended up blowing him apart with Grenades <3
I took this picture moments after a sniped a guy that was almost out of my sight.
Trying out my minigun. As you can see from the guy in the corner, everyone fled from the intimidating power of my minigun.
I ran into a bandit hideout, and they all had assault rifles. I ran out of ammo, so I fled.
Even amidst the liberation of a direlect bridge-top village, nothing is more important than a nice bathroom break.
As part of a quest, I was supposed to bring a message to these poor bastards from a long lost relative. How do I explain this?