MySQL binlog not logging

Have added the directive in my.cnf

log-bin

Both the binlog and index files are created, but seems the binlog file remain unchanged even I massively insert data into the db.

From serverfault Howard

• One possibility might be that if you are inserting into a transactional table but have not committed the data yet with a COMMIT statement all those inserts would be cached.

  From Kyle Brandt

• This may be a wild guess, but it sounds like this is either a secondary master or slave host? Add the following line to your my.cnf and restart mysqld:

  log-slave-updates
  

  From randy melder