main.log file not being updated

my postgresql-9.0-main.log log file is 0 bytes. Postgres user has perms to
write to it. And and postgresql.conf file shows to log, but it's not. Not
sure why.

I have the defaults set in except for these changes:

log_connections = on
log_disconnections = on
log_duration = off

log_line_prefix = '%t %p %h %d '
log_lock_waits = on
log_statement = 'none'

any ideas? I used to write log entries, but now, not so much.

Thanks.