A400P can't dial out

I'm using a A400P with 2 FXO and 1 FXS which attached to a normal phone. I'm using a trixbox. When I make local calls through the FXO, I hear ring tone on my side. When the other side pick up, they only hear dead air while I'm keep hearing ring tone like the other side didn't pick it up. However, when I use the phone to make calls through a VOIP internet provider to the same phone number, I have no trouble to get connected. It seems that the trixbox didn't realized the other side pick up the phone and didn't connect the FXS to the FXO. How can I solve this problem?

try immediate=yes in zapata.conf

Hi, I try immediate=yes, but still no luck. The following is the setting in zapata.conf, are there any changes that I should try? It seems to me that when the other side pick up, the system still didn't detect the pickup signal
;
; Zapata telephony interface
;
; Configuration file

[trunkgroups]

[channels]

busydetect=yes
callprogress=yes
answeronpolarityswitch=yes
hanguponpolarityswitch=yes
rtptimeout=8
rtpholdtimeout=12
busycount=5
language=en
context=from-zaptel
signalling=fxs_ks
rxwink=300 ; Atlas seems to use long (250ms) winks
;
; Whether or not to do distinctive ring detection on FXO lines
;
;usedistinctiveringdetection=no

usecallerid=yes
hidecallerid=no
callwaiting=yes
usecallingpres=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
cancallforward=yes
callreturn=yes
echocancel=yes
echocancelwhenbridged=yes
echotraining=100
rxgain=5.0
txgain=5.0
group=0
callgroup=1
pickupgroup=1
immediate=yes

;faxdetect=both
faxdetect=incoming
;faxdetect=outgoing
;faxdetect=no

;Include genzaptelconf configs
#include zapata-auto.conf

group=1

;Include AMP configs
#include zapata_additional.conf

I finally find the problem. I'm using freepbx, under the general settings, I put an "r" under the "Asterisk Outboud Dial command options" which is wrong and cause the problem.