File upload change name gives error

    $ref_id = mysql_insert_id();

$locatie = 'iso_photo/afwijkingen';

    if($_FILES['uploaded']['type'] != 'application/octet-stream')  // Geen php files
    {
        $folder = $locatie.basename($_FILES['uploaded'][$ref_id.'.jpg']) ;
        move_uploaded_file($_FILES['uploaded']['tmp_name'], $folder);
    }

Gives: Warning: move_uploaded_file(iso_photo/afwijkingen) [function.move-uploaded-file]: failed to open stream: Is a directory

Warning: move_uploaded_file() [function.move-uploaded-file开发者_如何学Go]: Unable to move '/tmp/php6LQCqY' to 'iso_photo/afwijkingen'

What might be wrong?

---

edited 4th line, should work now

$locatie = 'iso_photo/afwijkingen';

if($_FILES['uploaded']['type'] != 'application/octet-stream')  // Geen php files
{
    $folder = $locatie . "/" . basename($_FILES['uploaded'][$ref_id]) ;
    move_uploaded_file($_FILES['uploaded']['tmp_name'], $folder);
}

but can't properly say, as i don't know content of $ref_id variable