Migration to ZCS 8

I'm trying to migrate from ZCS Open Source 7.1.2 on a Ubuntu 10.04.2 LTS x86_64 to a ZCS Open Source 8 on Ubuntu 12.04.1 LTS x86_64 (servers are with different names).
I installed the ZeXtras Migration Tool on the old server, Version 1.6.0. I did the exportation (migration) of one domain on the old server to /opt/zimbra/backup/migration/, with no errors reported.
Than i did a rsync -Cravzp to the new server (/opt/zimbra/backup/migration/). On the new server I run Import Backup from ZxBackup, when asked for the Source Path : /opt/zimbra/backup/migration, and next, but on the Available I only have the default domain of the new server, not the domain exported on the old server.

Any idea?

Thanks