setting up cron for scheduled updates

Hi -

I am trying to set up a cron job to automate the update of listings.

Here is my crontab command:

0 3 * * * /usr/bin/env PATH=/usr/local/bin:/usr/bin:/bin COLUMNS=72 /usr/local/bin/drush --root=/var/www/sites/charlottesvillerealestate.us --uri=charlottesvillerealestate.us -u Charlottesville\ Real\ Estate -d rets-import

I can run drush rets-import fine from within the /var/www/sites/charlottesvillerealestate.us directory, manually.

Bootstrap to phase 0. [0.01 sec, 2.24 MB]                            [bootstrap]
Drush bootstrap phase : _drush_bootstrap_drush() [0.01 sec, 2.37 MB] [bootstrap]
Cache MISS cid:                                                  [debug]
5.1-commandfiles-0-e12e5b5c6003096558e6f2d3a914ce42 [0.02
sec, 2.38 MB]
Cache SET cid:                                                   [debug]
5.1-commandfiles-0-e12e5b5c6003096558e6f2d3a914ce42 [0.02
sec, 2.39 MB]
Bootstrap to phase 0. [0.07 sec, 5.27 MB]                    [bootstrap]
Bootstrap to phase 5. [0.08 sec, 5.27 MB]                    [bootstrap]
The drush command 'rets-import' could not be found.  Run         [error]
`drush cache-clear drush` to clear the commandfile cache if
you have installed new extensions. [0.08 sec, 5.27 MB]
The directory                                                    [error]
/var/www/sites/charlottesvillerealestate.us does
not contain a valid Drupal installation [0.08 sec, 5.27 MB]

I have run drush cache-clear drush a few times already and am still getting the above message on cron runs.

Anyone have luck getting cron to run the rets-imports?

Thanks!