mysql_numrows error

Warning: mysql_numrows(): supplied argument is not a valid MySQL result resource in /home/username/public_html//wp-content/plugins/coppermine_widget/ttc_coppermine_badge_widget.php on line 67

Does anybody know why I would get this error? I’m sure it’s something simple, but I don’t see why it wouldn’t work right out of the box, so to speak.