Exactly how are you trying to update? OTA (over the air) via the device? If so, instead try to update by connecting the device to your syncing PC with the latest version of iTunes installed.
http://www.apple.com/itunes/download/
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Exactly how are you trying to update? OTA (over the air) via the device? If so, instead try to update by connecting the device to your syncing PC with the latest version of iTunes installed.
http://www.apple.com/itunes/download/