You should, however, see the oils swirling on the surface of your drink if you look at it slightly from the side. You should also smell them when you raise the glass to your lips.
Don't know what kind of "twist" you're using, but try cutting off a quarter-sized (and shaped) piece of the peel from the side of your lemon (being careful to remove as little of the white pith underneath as possible). Hold this, peel side facing down, between your thumb and forefinger a couple of inches over the drink. Pinch the peel so that it bows downward in the direction of your drink. If it comes from a nice, fresh lemon, you should see a fine mist of oils expressed onto the drink. No actual "twisting" involved here. Don't forget to rub the peel around the rim of your glass afterward. What you do with it next is up to you (I drop mine in).