cacti: poller table and runtime problem.

http://forums.cacti.net/about29135.html
http://forums.cacti.net/about25765.html
http://www.cacti.net/downloads/docs/html/cli_poller_output_empty.html

1. Change Cacti log level to HIGH, or DEBUG.
2. run `php -q poller_output_empty.php`.
3. If the table problem solves, RRD should be processed normaly which shows GREEN in log.