asterisk users - Feb 2004 - Unable to specify channel 1: No such device or address

I can't start *. I'm receiving the following error:

 [chan_zap.so] => (Zapata Telephony w/PRI)
  == Parsing '/etc/asterisk/zapata.conf': Found
Feb 29 19:01:46 WARNING[1024]: chan_zap.c:673 zt_open: Unable to specify channel
1: No such device or address
Feb 29 19:01:46 ERROR[1024]: chan_zap.c:5324 mkintf: Unable to open channel 1:
No such device or address
here = 0, tmp->channel = 1, channel = 1
Feb 29 19:01:46 ERROR[1024]: chan_zap.c:7397 setup_zap: Unable to register
channel '1'
Feb 29 19:01:46 WARNING[1024]: loader.c:313 ast_load_resource: chan_zap.so:
load_module failed, returning -1
  == Unregistered channel type 'Tor'
  == Unregistered channel type 'Zap'
    -- Unregistered channel 1
Feb 29 19:01:46 WARNING[1024]: loader.c:408 load_modules: Loading module
chan_zap.so failed!

I'm running RH 7.3 in this box.

=======
lsmod:
Module                  Size  Used by    Not tainted
wcfxo                   8576   0  (unused)
zaptel                182816   0  [wcfxo]
soundcore               6692   0  (autoclean)
autofs                 12132   0  (autoclean) (unused)
sis900                 15108   1
ext3                   67136   2
jbd                    49400   2  [ext3]

=======
cat zaptel.conf
fxsks=1
loadzone=us
defaultzone=us

=======
cat zapata.conf
[channels]
busydetect=1
busycount=7
relaxdtmf=yes
callwaiting=no
callwaitingcallerid=no
threewaycalling=no
transfer=yes
cancallforward=yes
usecallerid=yes
echocancel=yes
echocancelwhenbridged=yes
rxgain=0.0
txgain=0.0
musiconhold=default

group=1
pickupgroup=1-4
immediate=no

context=bell
signalling=fxs_ks
callerid=asreceived
channel=1

=======
ztcfg -vv

Zaptel Configuration
=====================

Channel map:


0 channels configured.

^^^^^^^^^^
I don't believe this is normal, but modprobe zaptel and modprobe wcfxo
didn't return any error.

On the wiki pages it suggests that clients on the outside of NAT can connect
to an Asterisk server behind nat. (option no 3). The note suggests that this
can work with port forwarding and some 'header mangling magic'.

I have the port forwarding configured however, when I try to connect an
external client through the firewall the client does not correctly register.
The REGISTER message is received, the server responds with Status 100
trying, followed by Status 407 Proxy Authentication required. This repeated
several times.

I guessing but could this be where the 'header mangling magic' is
required.
? Does anyone know how this magic can be applied.

Many thanks
Steve Beaumont