We have just released a new version (v1.5) of our app on AppStore, this version was built using Xcode 4.6 using base SDK 6.1, supporting iOS 5.0 as minimum version. Now the
Apple is currently reviewing apps with iOS 7 devices. So they have (with very high probability) reviewed your app on an iOS 7 device. If the app has been recently released, then it may only be that servers need some time to refresh. If it has been a long time since the app was released (more than one day), then you should contact Apple support and ask them to see what is going wrong with their App Store system.