i dont know if it is a bug or a numeric conflict, i know numeric 489 as:

489 ERR_VOICENEEDED
<source> 489 <target> <channel> :You're neither voiced nor channel operator
returned when using the CNOTICE or CPRIVMSG command and you are not opped or voiced on the specified channel
from ircu / asuka source (undernet / quakenet)

when i use 'CNOTICE nick #channel :message' i get the following
in debug:
online2.no.quakenet.org cnotice nick #channel :.
online2.no.quakenet.org 489 wiebe #channel :You're neither voiced nor channel operator

in the channel / status window
* Unable to join channel (not using secure connection)

im using mirc 6.15