according to the mirc.hlp file, on *:SERVEROP:#:{ ... } does not support '^'
The ^ event prefix currently works only on the following types of events: ACTION, BAN, CHAT, DEHELP, DEOP, DEVOICE, HELP, INVITE, JOIN, KICK, MODE, NICK, NOTICE, OP, OPEN, PART, PING, TEXT, UNBAN, USERMODE, VOICE, QUIT, SERV, SERVERMODE, SNOTICE, TOPIC, WALLOPS.
Try removing it and see what happens.