If you are using SL Remote AI, this version if no longer used for current firmware versions. Download UC Surface from the App Store. This is the current version for current firmware versions.
iPhone 5 can still download and use QMix UC (current versions name) to control Aux mixes. UC Surface not available for phone devices, only tablets.
See article for Network Setup and Troubleshooting HERE.
If you have further issues, contact Tech Support via Support Ticket from your PAE Account.