Contacts won't restore from OS 10.4 backup
My iBook is pre-Intel running OS 10.4. My new Mac Pro has OS 10.8.
There's no support for iCloud in 10.4. To transfer my contacts, I backed up Address Book in 10.4 from the File menu, resulting in a backup file with the extension ".abbu." When I try to import that file into Contacts in OS 10.8, nothing happens other than erasing my personal V-card. I've repeated the process from start to finish several times, always with the same results.
Is there a fix for this, or a workaround? Thanks much!
Mac Pro, OS X Mountain Lion (10.8.3)