I would concur with the above. If you want to pop up a deadbait off the bottom ideally you want it just sitting up off the bottom, not floating up in mid water. That isn't to say that deadbaits presented in mid water won't catch. I've always thought they look rather unnatural but they do still catch pike. In the past I've had days when deadbaits fished on the bottom have been ignored but one fished way up off the bottom - usually on a sunken float paternoster - has produced.
One other thing; and I think this is really important. If you're using foam balls, balsa sticks, polystyrene or whatever, to make your bait buoyant, you need to consider preventing a pike from ingesting any of these materials; for example, if a bait came off on the cast. I would suggest attaching your pop-up material securely to your trace so that you always get it back again - even if you lose your bait.