Very interesting, the following link is using virtual aliases on my 1.0.4 modx install
http://www.stanback.net/freeware.html.
I should try setting it up with a virgin install of 1.0.4, I wonder if there is some database schema difference that is being retained from my upgraded copy. My copy is also running under Lighttpd which might alter things.
Without access to your specific installation, and without being able to reproduce the issue myself, a fix is something of a shot in the dark. If you do an "echo $modx->db->getRecordCount($results);" (I think, I’ve been using XPDO far too much lately), is it coming back with 1 or more results?
(I also assume the value of $documentAlias matched the aliases you defined (one per line) in the TV of the target document.)