The only possibility is that the remote userid you used to make the test
is an owner of the list (or a postmaster for LISTSERV). In that case,
since the issuer of the command has the privilege to add himself with an
ADD command, LISTSERV doesn't ask the other owner(s) to do it for him.
The SUBSCRIBE is refused so as not to cause panic among the ranks of
owners who want to "make sure that the list is indeed closed" :-)
Eric