error while communicating with nimbus

Hi,

First of all, I am using sandbox 2.1.
And I have a storm related problem with one of tutorials which can be found at the URL listed below.

http://hortonworks.com/hadoop-tutorial/real-time-data-ingestion-hbase-hive-using-storm-bolt/

It gives me an ‘error while communicating with nimbus’ error when I try to deactivate or kill a topology from storm UI.
BTW, It was OK at sandbox 2.2. previewer.

Best regards,

– Mungeol