[eluser]jedd[/eluser]
I don't know - I just popped in for the syntax error. I've never used
echo $this->db->_error_message();, but just went exploring, found the reference in system/database/DB_driver, and then tested it in my model. It doesn't error (presumably I have no errors to report) but OTOH it doesn't produce the error you're getting either.
Are you
really sure you're loading the database library?