I've been having massive trouble with getting SirWags to touch the plexiglass on a flat surface and an upright surface without me holding the thing. He'll do it on the ground or if it's low enough for him to see. If he has to look for it, it's not connecting in his mind.
So, I'm holding it against a piece of furniture. Everytime he touches it, I angle it a bit more. We get about halfway through, so it's halfway on the piece of furniture before he gives up. That's still better than before, and I think just a couple days of practice will be what he needs to make that connection.
We've switched to a piece of plexiglass for him to target on, because once he's used to targeting that, we can put that plexiglass on a piece of furniture, and he'll target there, or against a lamp, and he'll target there, ideally. So in the real world, he'll target wherever there's a sound and come to target me that it's there. Except the fire alarm, he has to target me and the front door, not the alarm itself.