Site alias not found

My apologies if this is not the right place for this.

I have code similar to the following in aliases.drushrc.php:

$aliases['phmx7'] = array(
'root' => '/www/phmx7',
'uri' => 'phmx7.mydomain.edu',
'db-url' => 'mysql://phmxx:dbpword@mydomain.edu/phmx7',
);

This file is located in /home/myhome/.drupal

When I run drush site-upgrade @phmx7 the process begins normally, displays the UPGRADE.txt Major Upgrade Step 1 information but after that I get - Site alias not found: @phmx7. See example.drushrc.php.

I have found here on Drupal.org and elsewhere where others had the same issue, but the steps that resolved their problems have done nothing to resolve mine. I've run out of ideas. Any suggestions will be most welcome.

Thanks.