cache_delete() not working

[eluser]ibnclaudius[/eluser]
I'm trying to delete a specif cache, but is not working. By the way, delete all works pretty well.

Code:

$this->db->cache_delete_all();

The cache is saved in site+index folder, so I'm doing this:

Code:

$this->db->cache_delete('site', 'index');

My database cache config:

Code:

$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = 'application/queries/';

The cache is manually active right before the select, and after a insert I try to delete that specific cache...