Cactiusers.org

hi,
after i add a router into ,the router status is unknown ,and the router is reachable, when i create a graph , RRD files can not be created. why ?
the following is Cacti Log File:
10/16/2009 09:00:01 AM - POLLER: Poller[0] WARNING: Cron is out of sync with the Poller Interval! The Poller Interval is '60' seconds, with a maximum of a '300' second Cron, but 120 seconds have passed since the last poll!
10/16/2009 08:58:02 AM - SYSTEM STATS: Time:1.2409 Method:spine Processes:1 Threads:1 Hosts:2 HostsPerProcess:2 DataSources:6 RRDsProcessed:6
10/16/2009 08:57:03 AM - SYSTEM STATS: Time:1.2406 Method:spine Processes:1 Threads:1 Hosts:2 HostsPerProcess:2 DataSources:6 RRDsProcessed:6
10/16/2009 08:56:03 AM - SYSTEM STATS: Time:1.3506 Method:spine Processes:1 Threads:1 Hosts:2 HostsPerProcess:2 DataSources:6 RRDsProcessed:6
10/16/2009 08:56:01 AM - POLLER: Poller[0] WARNING: Cron is out of sync with the Poller Interval! The Poller Interval is '60' seconds, with a maximum of a '300' second Cron, but 120 seconds have passed since the last poll!