The other thing to keep in mind is that skimmers take a few days to "break in" so any adjustments that you make might take a wee bit of time to show up. If you aren't getting any bubbles in the skimmer body at all, then you aren't getting air, if the air intake is in the water...
If you aren't getting bubbles up into the collection cup, wait a few days without tinkering and see if you get any junk in there.