$wpdb->query can’t insert data

The following code will properly store data in wp_fafa:

$wpdb->insert( $wpdb->prefix . 'fafa', 
    array( 
        'title'     => trim($row->item(0)->nodeValue),
        'liveprice' => trim($row->item(2)->nodeValue),
        'changing'  => trim($row->item(4)->nodeValue),
        'lowest'    => trim($row->item(6)->nodeValue),
        'topest'    => trim($row->item(8)->nodeValue),
        'time'      => trim($row->item(10)->nodeValue)   
    ), 
    array( 
        '%s',
        '%s',
        '%s',
        '%s',
        '%s',
        '%s'
    ) 
);