HDFS connection issue on a Kerborized cluster

I installed Toad for Hadoop 1.5.1.  Thanks for the software.  But my cluster is Kerborized and I could able to connect Hive and Charts.  But HDFS is giving the wrong principal name, even though my principal name is hdfs-server@realm, but configuration is showing nn-server@realm.  Not sure where it is getting nn-?  Is there anyway you can help.

Thanks