Just since I posted it in the other thread - the QR code goes here:
http://qr.disneyworld.com/PhotoPassReminderGuardians?r=qr
Having looked at this again, I think most people's problem is likely giving the
app permission to use Bluetooth. It's not enough to just turn Bluetooth on - the app has to explicitly have permission to use it.
Not sure about iPhone, but on Android, if you long-press the app icon, then click the info icon ("i" in a circle), it'll take you to the application page. From there, hit Permissions, and make sure Nearby Devices is set to Allow.