Meaning of Handle is unknown to the system

Q. I got exceptions while using JTAPI application.

Exceptions are as below:

InvalidStateException:Handle is unknown to the system

PlatformException:Handle is unknown to the system

What is meaning of message Handle is unknown to the system?

Why there is same message for two different ecxeptions?

It is mentioned in the section New error code in CiscoTermRegistrationFailedEv  of  Cisco Unified JTAPI Developers Guide for Cisco Unified Communications Manager Release 10.0(1) as follows:

This event is sent to application when TerminalRegistration fails for some reason. The return value of getErrorCode() interface indicates the type of failure. On receiving this event, application should try to reregister the Terminal. In this version a new return value is added to this interface. CiscoTermRegistraionFailedEv.UNKNOWN is introduced in this version to handle unknown failures.