Problem with wi-fi sync

For the first day or so, the wi-fi sync app worked perfectly. now, for some reason, it's no longer working properly. when i run the app, i do get the "ready to sync" screen on the ip4 and i get the green colored icon on the menu bar on my imac so I know they are paired, but for some reason, my phone does not appear in itunes.

anyone have any idea why this is happening and how to correct it? I have tried opening the app and then itunes, i've tried opening itunes then the app, and i've tried resetting the paired devices on the imac. Hoping one of you has a solution.

TIA