Error during command authentication.
Error - unable to initiate communication with LISTSERV (errno=10061, phase=CONNECT, target=127.0.0.1:2306). The server is probably not started.
LISTSERV 16.0 - TSE Archives
Those classes also might be special topics classes -- check the descriptions as well. Often departments have a limit to how many times you can take a class -- best to call the department secretary.