using of get_entities()


I'm using elgg 1.7, and I try to learn how to develope a plugin. I have a question again about the get_entities method.

I read the reference to understand the usage of this method, but something is not clear for me.

My piece of code:

// I get the user ID

$user_guid = get_loggedin_userid();

// ... and  I try to select all object, with the subtype 'my_subtype', to the current loggedin user.
$q = get_entities(array('type '=>'object', 'subtype'=>'my_subtype', "owner_guids"=>$user_guid));

If I try print_r($q), then I get not just the elements with the subtype: my_subtype, but all elements with the type: object.

What should I do to get from the database what I want?

Thanks for any help!