Determine if this is an application program error (if the application program returns a different invoke id value than was passed to it in the original message). Fix the application program error if that's what it was. If the invoke id value was valid, check to see if there were any error messages logged to indicate that the Association/Session was aborted. If it was, determine if there is any action you can take to prevent it from happening again. If there was no error logged, then the Association/Session was aborted in a "normal way". CMIP services will reject the message and continue processing.