about load->database

Hello, my project must connect database from other place maybe 2-4 db so I need show news from other db.

And I want to know connect database is success or fail.

example in my model

PHP Code:

$this->ora = $this->load->database('luck', TRUE); 


and i do this ... but not work it load oracle a long time and error 500

PHP Code:

if ($this->load->database('luck', TRUE)) 
{
    return false;
} 


now, What i can do check connect database.
thank you.

(my english is very bad, sorry >,,<)