com.tailf.cdb.CdbException: Unknown CDB operation

I am writing a program in Java that subscribes to changes in CDB. I want to subscribe to all the changes but for starter any particular path will also work.

Following is the code snippet I have written following the practices defined for tailf CDB API in NSO documents:

Socket socket;
        Cdb cdb;
        try {
            socket = new Socket("localhost", 4570);
            cdb = new Cdb("MyCdbSock", socket);
            CdbSession session = cdb.startSession();
            CdbSubscription subscription = cdb.newSubscription();
            int subid = subscription.subscribe(CdbSubscriptionType.SUB_RUNNING, 1, new Ncs(), "/");

This code throws an error on the subscription.subscribe line, with following execption:

com.tailf.cdb.CdbException: Unknown CDB operation
	at com.tailf.cdb.CdbSubscription.subscribe(
	at com.tailf.cdb.CdbSubscription.subscribe(
	at com.tailf.cdb.CdbSubscription.subscribe(

Anyone knows what is wrong here? The error does not give much details. The java program is not running inside the NSO java vm. It is a standalone application.

you can check working example in ConfD examples package - ${CONFD_DIR}/examples.confd/intro/java/1-2-3-start-query-model
for potential differences form your code that could be causing the problems…

(you seem to have different number/type of parameters in subscription.subscribe() method, compared to original example…)

Thanks @josephm

Yes, I had different number and type of parameters, but changing it did not help. However, I removed the creation of CdbSession line and it worked fine. I am still not sure why that can be a problem but apparently that was the reason.