My 4S and previous 4 won't backup to iCloud. I have the backup switched on in Settings. The screens below always say "There was a problem completeing the backup. Please try again later. Last Backup: Never" and "Last Backup Incomplete". When I tap "Backup Now" I get the same results. The status bar shows there is 600 MB in storage in iCloud. Can anyone see or figure out what I'm doing wrong?