I have a query and im getting errors with it...

PHP Code:
$query="SELECT b.*, c.* FROM tod_company_information c INNER JOIN tod_bookings_archive b ON c.company_id = b.company_id $filter_string WHERE b.date_fitted < DATE_SUB(now(),INTERVAL 1 YEAR)ORDER BY b.date_in ASC"
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/eeeepcom/public_html/tt/main.php on line 23

any ideas

Thanks in advance

crE