Drush ard is working for D6, not for D7 > bootstrap error Noticed something strange today:

drush ard @sites is working in the folder /drupal6/sites/, but not in /drupal7/sites/. When i go to a specific folder, the command runs as expected (drush ard foobar.com in /drupal7/sites/foobar/)
So, Drush is working ;-), it's working in Drupal 6 but not in 7. Can someone advice me where to look? Did some googling, but i can't find a good answer. 

Drush status gives

Drupal version                  :  7.26
Site URI                        :  http://foobar.com
Database driver                 :  mysql
Database username               :  [username]
Database name                   :  [databasename]
Database                        :  Connected
Drupal bootstrap                :  Successful
Drupal user                     :  Anoniem
Default theme                   :  Garland
Administration theme            :  Garland
PHP executable                  :  /usr/bin/php
PHP configuration               :  /etc/php5/cli/php.ini
PHP OS                          :  Linux
Drush version                   :  6.1.0
Drush configuration             :
Drush alias files               :
Drupal root                     :  [path to root]
Site path                       :  [path to site]
File directory path             :  [path to files]
Private file directory path     :  [path to files]
Temporary file directory path   :  tmp


The error with drush -d ard @sites is:

Command archive-dump needs a higher bootstrap level to run
- you will need to invoke drush from a more functional Drupal 
environment to run this command*
This seems like a permissions' issue on your server. Make sure that the user that you are running the command as, has the appropriate permissions in the Drupal 7 directory.

An easy way to fix it is change the owner of the Drupal7 dir by using something like:

chown -R username:usergroup /path/to/drupal7/dir


or if you are working in a debian based environment you can run the command with super-user-do like:

sudo drush ard