Server not showing up on master list

Hi,

I run a TF2 dedicated server on windows. However, the server does not show up on the master list. I can still connect to it without problem by the console command 192.168.1.5:27016.

Code of my server.cfg:
hostname "scott"
sv_tags "scott"
mp_timelimit "30"
sv_alltalk 0
sv_lan 0
sv_rcon_maxfailures 5
sv_rcon_banpenalty 1440
exec banned_user.cfg
exec banned_ip.cfg
writeid
writeip
log on
sv_log_onefile 0
sv_logfile 1
sv_logbans 1
sv_logecho 1
sv_allowdownload 1
sv_allowupload 1
mp_autoteambalance 1
mp_teams_unbalance_limit 1
mp_allowspectators 1
heartbeat

Code of my tf.bat: (to start the server)

C:/tf2servers/pipeserver/srcds.exe -game tf -maxplayers 16 +map cp_dustbowl

Thanks.