[support] changing online/offline mode via db or settings.php doesn't work

[Daniel Caillibaud]

Hello,

On a drupal 6.6 multisite installation, I can't change the online status with
- changing the site_offline value (`s:1:"1";` or `s:1:"0";`) in the variable table
- adding $conf['site_offline'] = 's:1:"0";'; (or $conf['site_offline'] = 's:1:"1";';) in my settings.php
and I don't understand why!

When I change the status by the "normal" way (admin/settings/site-maintenance), the only change in the variable table are (by
diff on 2 dumps):
  before (online)
INSERT INTO `dev_variable` VALUES ('site_offline','s:1:\"1\";');
INSERT INTO `dev_variable` VALUES ('cache_flush','i:1225586663;');
  after (offline)
INSERT INTO `dev_variable` VALUES ('site_offline','s:1:\"0\";');
INSERT INTO `dev_variable` VALUES ('cache_flush','i:1225587127;');

Any idea ?

PS:
- I'm sure I'm changing the right table (when I change the status with admin/settings/site-maintenance, I see the value change)
- I'm sure I'm changing the right settings.php (I made a syntax error to test)

-- 
Daniel