cannot enable apc: apc_cache_info(): No APC info available

Hi,

APC is enabled for apache (/etc/php5/conf.d/apc.ini) and /var/www/apc.php reports it as running and caching on the apache level. Calling phpinfo() from a webpage also shows that it is running.
After downloading this module and updating settings according to the README:
$conf['cache_backends'] = array('sites/all/modules/apc/drupal_apc_cache.inc');
$conf['cache_class_cache'] = 'DrupalAPCCache';
$conf['cache_class_cache_bootstrap'] = 'DrupalAPCCache';

I then try to enable the module via drush:
drush en apc
WD php: Warning: apc_cache_info(): No APC info available. Perhaps APC is not enabled? Check apc.enabled [warning]
in your ini file in DrupalAPCCache->clear() (line 239 of
.. modules/apc/drupal_apc_cache.inc).
apc_cache_info(): No APC info available. Perhaps APC is not enabled? Check apc.enabled in your ini file [warning] in DrupalAPCCache->clear() (line 239 of .../modules/apc/drupal_apc_cache.inc).

Next apc was enabled in the modules gui, there was no complaint in the GUI, although in watchdog the above message appeared again.

Some version infos: Running APC Version 3.1.9 on PHP 5.3.2-1ubuntu4.10 (Ubuntu Lucid)

Also: does this apc module itself provide stats somewhere, or does one just use apc.php to see what is going on in the cache?