Although SIC was already established and running, Joe reset SIC between the Security Management Server and a remote Gate

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Although SIC was already established and running, Joe reset SIC between the Security Management Server and a remote Gateway. He set a new activation key on the Gateway's side with the command cpconfig and put in the same activation key in the Gateway's object on the Security Management Server. Unfortunately,
SIC can not be established. What is a possible reason for the problem?

A. The installed policy blocks the communication.
B. The old Gateway object should have been deleted and recreated.
C. Joe forgot to exit from cpconfig.
D. Joe forgot to reboot the Gateway.