No db results on staging server?

[eluser]kilishan[/eluser]
Here's a new one to me.

Code is working fine on my development box, but when it gets uploaded to the staging server for testing, it seems that nothing that ever connects to the database ever gets any information back. Every place that it does

Code:

if ($query->num_rows() > 0)
{ ... }

it's giving me a fatal error

Code:

PHP Fatal error:  Call to a member function num_rows() on a non-object

The staging server is runnig Ubuntu 10, PHP 5.3.2 and MySQL 5.1.41. The db config file is set to:

Code:

$db['test']['hostname'] = "localhost";
$db['test']['username'] = "...";
$db['test']['password'] = "...";
$db['test']['database'] = "...";
$db['test']['dbdriver'] = "mysql";
$db['test']['dbprefix'] = "";
$db['test']['pconnect'] = TRUE;
$db['test']['db_debug'] = TRUE;
$db['test']['cache_on'] = FALSE;
$db['test']['cachedir'] = "";
$db['test']['char_set'] = "utf8";
$db['test']['dbcollat'] = "utf8_general_ci";

(username, etc removed)

Any ideas what would be causing this? There is data in the database, same as the db on the dev server...