I do similar with my pillies too at times. If your missing the hook up Andy it could be your picking the rod up too quick. I leave the drag a little loose and let them pull for a little bit before I pick up.
Some say the first whack is often the Kahawai hitting the float and then they come back for the bait. I'm not so sure but I do know quickly grabbing the rod on the first hit can often lead to an empty line. Kahawai can be as picky as any fish at times.