Hello Gaurav,
I got a similar "Invalid Index" error when I connected to a JBoss server that had no JMS enabled. But before the "Invalid Index" error was shown, a whole bunch of other errors was also shown in the log-window, e.g.:
javax.management.InstanceNotFoundException: jboss.messaging:service=ServerPeer is not registered.
To start JBoss 5.1 with JMS, try starting JBoss with "run -c all". This might solve your problem.
I think the tool expects at least 1 registerd queue and will give the "Invalid Index" error if there are no queues (or could not retrieve the queues from JBoss).