If you are certain you have the correct serial numbers take a look at this Troubleshooting Professional Application Serial Numbers
If that still doesn't work and you have the original install media then you should install from that. Pro Apps really don;t do well being migrated .
Note even if your 3 version is an upgrade from 2 you ONLY need to install the 3 DVD. You will need the version 2 serial number as well as the serial number for 3 but you only need to load the 3 DVD. Once you install from the DVD run software upgrade to get to the latest version
How did you migrate Aperture? Did you reinstall it or simply migrated it using Migration assistant? Pro Apps are best reinstalled using the installation media. You can reinstall directly the Aperture 3 upgrade and then update to the current version using Software update.
See this: http://support.apple.com/kb/TS2005
Check, if all letters are typed correctly. Don't use the numerical keypad to enter the numbers and check if caps lock is accidentally enabled.
Enter all serial numbers for all previous versions, beginning from Aperture 1, if your Aperture 2 is an upgrade.
If you cannot get Aperture to accept your serial number, contact Apple: Pro Application Replacement Serial Numbers
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Thank you. I can't uninstall & reinstall because mine are CD/DVD and there is not slot for those on the new imacs.
Jana, you can use the Aperture Trial to reinstall. It will install the same Aperture version as your Aperture 3 disk.
Ah yes the new age of no DVD! There is a link Aperture 3.1 Trial that will let you download the old Trail version. You can unlock it with your serial numbers.
Also if you have Mac or PC with a DVD drive in your network you can use that drive on your Driveless Mac over the network.
Message was edited by: Frank Caggiano - Seems there is a bit of a delay in posts showing up today.