problem connecting to postgres

Hello!

I am trying connect to postgres, but doesn't work. In my database.php I have something like

$db['default']['hostname'] = '192.168.0.207';
$db['default']['username'] = 'postgres';
$db['default']['password'] = 'rontur';
$db['default']['database'] = 'stand';
$db['default']['dbdriver'] = 'postgre';
$db['default']['port'] = '5432';
$db['default']['dbprefix'] = '';
$db['default']['pconnect'] = TRUE;
$db['default']['db_debug'] = TRUE;
$db['default']['cache_on'] = FALSE;
.........................................

Now, if I try connect using odbc, it works!,

$db['default']['hostname'] = 'DRIVER={PostgreSQL ANSI};SERVER=192.168.0.207;DATABASE=stand';
$db['default']['username'] = 'postgres';
$db['default']['password'] = 'rontur';
$db['default']['database'] = 'stand';
$db['default']['dbdriver'] = 'odbc';

any idea?

Best Regards
Fernando