Rebuild fails when target database is empty.

I am trying to rebuild from an empty database and sql-sync is failing.

Syncing database from @xyz.prod to @xyz                                                                                                                                                                                                          
The drush command '@xyz sql-sync @xyz.prod @xyz' could not be found.  Run `drush cache-clear drush` to clear the commandfile cache if you have installed new extensions.                                                                          [error]
Drush was not able to start (bootstrap) the Drupal database.

If you remove the first @xyz this should work.