Fatal error with get_where()? need help

[eluser]Zimooon[/eluser]
Hey guys im getting an error and don know how to fix it someboday know what 2 do?

Code:

A PHP Error was encountered

Severity: Notice

Message: Undefined property: Newstest::$db

Filename: core/Model.php

Line Number: 50

Fatal error: Call to a member function get_where() on a non-object in \application\models\newstest_model.php on line 23

Line 23 is this:

Code:

public function getOneNews($nid){
        
        $query = $this->db->get_where('news',array('news_id'=>$nid));
        return $query->row(0);
     }
}

hope you can help me.

best regards