Hello, I recently had my 4S stolen and bought an iPhone 4 off craigslist. When I try to restore (on version 5.0.1) I'm getting an error regarding "iPhone could not backup because backup file was corrupt or not compatible". Do I need to upgrade to 5.1.1 in order to do the backup? Any advice? I even tried my old iPhone 4 backup from last year and that failed too.