I can't upgrade to 12.10 Quantal Quetzal

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http://askubuntu.com – After hearing about some of the features in 12.10, I decided to upgrade my Ubuntu from 12.04 LTS to the newer 12.10. However, when I try to upgrade it, I start the update manager, like always, and I start the distro upgrade, just like I do every time there's a new version, but at the end of the "Setting new software channels" stage, it fails, saying: Could not calculate the upgrade An unresolvable problem occurred while calculating the upgrade: E: Unable to correct problems, you have held broken packages. This can be caused by: Upgrading to a pre-release version of Ubu (HowTos)