Is there some restriction on which device you can rate from? I like to browse the iOS app store via iTunes from my MacBook, so I often stage apps there for download on the next sync with my iPhone. I just tried to rate a so-installed app from my iPhone and (after typing in and submitting a review) it said that I need to own the app before I can review it. Is there some sort of synchronization that I have set inappropriately?
If you buy the same app using the same iTunes account from different iOS devices, you can rate the app from any of the devices. Synchronization is done between the device you rated the app and Apple's iTunes App Store.