Music Hold Problem

Hi everybody,
I have installed ASterisk and it´s working correctly, now i want to configure MUSICHOLD.
I configure zapata.conf, musiconhold.conf and extension.conf as show all instruccions in asteriskguru.com or voip.org page.
Then i created a extension (2000) to test it.
But it isn´t working. I can´t heard anything.
I have mpg123 too.

I hope that somebody can help me!!!

thks.
Pablo

What is the output of the cli when you dial 2000

no music when i dial 2000
this is the extension config

exten => 2000,1,Answer
exten => 2000,2,SetMusicOnHold(default)
exten => 2000,3,WaitMusicOnHold(20)
exten => 2000,4,Hangup