Trying to restore my iMac from Time Capsule after reinstalling the OS X

Had to reinstall the OS after replacing the power supply and finding the OS corrupted. Originally the iMac came with 10.4.7 which we upgraded to 10.6.8. Now trying to restore the data from my time capsule using migration assistant only to get the message that the backups were done with a newer version of OS X. I checked the version installed and it's up to date.

How can I get the data and how is it possible that the version is newer given that the same disks were used??