asterisk users - Mar 2006 - Attended transfer returns invalid extension

Hello,

I am trying to set up a slim Asterisk. Blind transfer works, and attended
transfer always plays "pbx-transfer", then I dial the extension and it
plays "pbx-invalid". Here is my modules.conf :

; * Resources *
load => res_features.so
load => res_adsi.so
load => res_monitor.so
load => res_musiconhold.so
; * PBX *
load => pbx_config.so
; * Channels *
load = chan_sip.so
; * Codecs *
load => codec_gsm.so
load => codec_ulaw.so
; * Formats *
load => format_gsm.so
; * Applications *
load => app_db.so
load => app_dial.so
load => app_macro.so
load => app_playback.so
load => app_transfer.so

My extensions.conf is quite bigger, I use some macros and different
contexts. But I do not understand why blind transfer works while attended
transfer returns invalid extension. Do I miss a module ?

Please help,

Alexis F?court