Cassandra Opscenter, No data collected

you might get this, the ring is correct, no data get collected from agent,

If you check log /var/log/opscenterd.log

2012-03-28 16:20:43-0700 [] Problem while calling MetricsController         Traceback (most recent call last):         Failure: telephus.cassandra.c08.ttypes.InvalidRequestException: InvalidRequestException(why='range finish must come after start in the order of traversal') 2012-03-28 16:20:44-0700 [] Problem while calling MetricsController         Traceback (most recent call last):         Failure: telephus.cassandra.c08.ttypes.InvalidRequestException: InvalidRequestException(why='range finish must come after start in the order of traversal') 2012-03-28 16:20:45-0700 [] Problem while calling MetricsController         Traceback (most recent call last):         Failure: telephus.cassandra.c08.ttypes.InvalidRequestException: InvalidRequestException(why='range finish must come after start in the order of traversal') 2012-03-28 16:20:46-0700 [] Problem while calling MetricsController         Traceback (most recent call last):         Failure: telephus.cassandra.c08.ttypes.InvalidRequestException: InvalidRequestException(why='range finish must come after start in the order of traversal') 2012-03-28 16:20:47-0700 [] Problem while calling MetricsController         Traceback (most recent call last):         Failure: telephus.cassandra.c08.ttypes.InvalidRequestException: InvalidRequestException(why='range finish must come after start in the order of traversal') 2012-03-28 16:20:48-0700 [] Problem while calling MetricsController         Traceback (most recent call last):         Failure: telephus.cassandra.c08.ttypes.InvalidRequestException: InvalidRequestException(why='range finish must come after start in the order of traversal') 2012-03-28 16:20:49-0700 [] Problem while calling MetricsController         Traceback (most recent call last):         Failure: telephus.cassandra.c08.ttypes.InvalidRequestException: InvalidRequestException(why='range finish must come after start in the order of traversal')

Basically, this means the time setting is incorrect, between the cluster nodes and your client machine, here will be the browser.