If you have the cards in any other order than,1) Core2) Process3) Processthe Core card might not be set up as the master. Look at the configuration and verify where the TDM flex cable is connected. The card with the A port open is the default Master. This should be the Core card, but because the system can be configured with a different card order ( Not supported ) the system would continue to function but the Default master would be where the empty A port is.