Control from iOS remote on iPhone 4s

Trying out Proclaim for the first time. I've just downloaded the iOS app on my iPhone 4s, Proclaim running on Windows 7. I start the presentation on the PC and the iOS app sees it and lets me control it. But when I control it, I can't actually switch any slides. I can select other slides in the iOS app but nothing changes on the PC and after a few seconds the iOS app displays the message, "Unable to change slide".
Any tips that I can try? We currently use a mix of OpenSong for our song presentation, controlled by the people in the sound booth, and Keynote for things I want to show in my sermon, controlled by me via the Remote app on my iPhone so I can switch while preaching at my own pace. Thus I'd like to continue to have the ability to change slides remotely, and the Proclaim Remote app should fit the bill - if I can get it working. I have yet to see it actually change a slide.