In the beginning, you have to "charge" the pad by banging it with the lid on pretty hard to get the powder flowing in the correct direction. Basically, when you see a good amount of powder start to show up on the pad, you should be ready to go. Before each swipe, you have to charge it again by banging it once or twice. Leah Day has a good demo video on Youtube.
I do find that I have to swipe/rub it back and forth a couple times over the stencil to get it to show well. I press down fairly firmly as I swipe. Maybe my eyes aren't that good. You need to hold the stencil down really well too, so that it doesn't shift while you swipe.
I mark small sections at a time, and after marking, I spray with spray hairspray. It seems to help set the powder long enough to quilt it. If you're having problems with your hopping foot bouncing the powder right off, you could try modifying your foot so that it hovers over the quilt sandwich like
Leah Day does?