Syntax in function does not work

Hi,

I have the problem with CodeIgniter syntax in function.

It works:

$value = $this->db->query("SELECT * FROM `z_kinds`");
echo $value;

It does not work:

function value() {
$value = $this->db->query("SELECT * FROM `z_kinds`");
return $value
}

I have to use only:

function value() {
$value = mysql_query("SELECT * FROM `z_kinds`");
}

I want to use syntax $this->db->query and not mysql_query.

What do I have wrongly?

Thanks very much.

L