Fax Issue

Hello,

We're using asterisk 1.4.18 , zaptel 1.4.11 and D110P but we've faced to fax issue , sometime we aren't able to send/receive fax on the PRI. please see the below configurations. any advice would be appriciated.

Thanks,
Mehrdad
=========================

Zapata.conf

;!
;! Automatically generated configuration file
;! Filename: zapata.conf (/etc/asterisk/zapata.conf)
;! Generator: Manager
;! Creation Date: Mon Nov 17 18:01:06 2008
;!
[channels]
switchtype = euroisdn
pridialplan = national
signalling = pri_cpe
usecallerid = yes
hidecallerid = no
callwaiting = yes
callwaitingcallerid = yes
threewaycalling = yes
transfer = yes
cancallforward = yes
echocancel = yes
rxgain = -1
txgain = 0
group = 1
callgroup = 1
pickupgroup = 1
immediate = no
callprogress = no
callerid = asreceived
group = 1
signalling = pri_cpe
channel = 1-15,17-31
faxdetect = incoming

Zaptel.conf

#span=1,1,0,ccs,hdb3
#bchan=1-15,17-31
#dchan=16
#defaultzone=nl
#loadzone=nl

# Span 1: WCT1/0 "Digium Wildcard TE110P T1/E1 Card 0"
span=1,1,1,ccs,hdb3
# termtype: te
bchan=1-15,17-31
dchan=16
# Global data
loadzone = us
defaultzone = us

hello:
can you show us the errors or logs and dialplan?
regards!
James.zhu