what am I doing wrong?

gistfile1.txt

function seoslides_pre_user_query( $query ) {
  if( 'DateRegistered' == $query->query_vars['orderby'] ) {// echo 'thus far';
		$query->query_from .= " LEFT JOIN wp_usermeta m ON (wp_users.ID = m.user_id  AND m.meta_key = 'user_registered')";
		$query->query_orderby = "ORDER BY m.meta_value " . $query->query_vars['order'];
	}
}
add_action( 'pre_user_query', 'seoslides_pre_user_query' );

function seoslides_manage_users_columns( $columns ) {
	$columns['user_registered'] = 'Date Registered';
	return $columns;
}
add_filter( 'manage_users_columns', 'seoslides_manage_users_columns' );

function seoslides_manage_users_sortable_columns( $columns ) {
	$columns['user_registered'] = 'Date Registered';
	return $columns;
}
add_filter( 'manage_users_sortable_columns', 'seoslides_manage_users_sortable_columns' );

function seoslides_manage_users_custom_column( $value, $column_name, $user_id ) {
	$user = get_userdata( $user_id );
	return $user->$column_name;
}
add_action( 'manage_users_custom_column', 'seoslides_manage_users_custom_column', 10, 3 );