Leppink

Managed to fix this issue.

replace the following:

function order_by($key, $sort = 'ASC') {
        $this->order_by = ' ORDER BY <code>' . $key . '</code> ' . $sort;
    }

with

function order_by($key, $sort = 'ASC') {
        $this->order_by = ' ORDER BY ' . $key . ' ' . $sort;
    }

in

wp-content/plugins/rich-reviews/lib/nmdb.php