Announcements always played in english

Hi, I recently installed vicidialnow and purchased the manager and agent manuals. I was trying to make it work in spanish so I installed the spanish announcements and set language='es' in all asterisk configuration files. No matter what I do, announcements are always played in english instead of spanish (i.e. 'You are currently the only person in this conference')
I have tested the right configuration of agent's language calling to a extension (555) confgiured to play the 'invalid' announcement,
and the result was the expected behaviour (announcement is played in spanish,
so the problem sems to have something to do with vicidial.
Can anybody help me please?
== Manager 'sendcron' logged off from 127.0.0.1
-- Executing MeetMe("IAX2/cc301-5", "8600051|F") in new stack
== Parsing '/etc/asterisk/meetme.conf': Found
-- Created MeetMe conference 1023 for conference '8600051'
-- Playing 'conf-onlyperson' (language 'en')
I have tested the right configuration of agent's language calling to a extension (555) confgiured to play the 'invalid' announcement,
exten => 555,1,Background(invalid)
exten => 555,n,Hangup
and the result was the expected behaviour (announcement is played in spanish,
-- Executing BackGround("IAX2/cc301-3", "invalid") in new stack
-- Playing 'invalid' (language 'es')
so the problem sems to have something to do with vicidial.
Can anybody help me please?