asterisk users - Nov 2004 - TDM400P callwaiting, threewaycalling and cancallforward problem

Hi,

I have a TDM400P with one FXO and an FXS. My Australian telco has enabled 
call waiting and three way calling.

When I'm using my telephone connected to the FXO I can see/hear on my 
handset that call waiting is enabled, however when I attempt to send a hook 
flash or use the combination "*0" I don't get a dialtone and the
feature
doesn't work. The same goes for three way calling and cancallforward.

I hope someone can explain to me what may be going on as it's been something
I haven't been able to solve. My zapata conf is below.

zapata.conf
[channels]
busydetect=yes ; to test when a line is hung-up
busycount=6 ; to prevent suprious hangups
echotraining=800
echocancel=yes
immediate=no
usecallerid=yes
relaxdtmf=yes
callwaiting=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
cancallforward=yes
callerid=asreceived

signalling=fxs_ls
group=1
context=PSTN
channel => 4

signalling=fxo_ls
mailbox=1
callerid="Real Phone" <1>
context=RealPhone
channel => 1

>When I'm using my telephone connected to the FXO I can see/hear on my 
>handset that call waiting is enabled, however when I attempt to send a hook
>flash or use the combination "*0" I don't get a dialtone and
the feature
>doesn't work. The same goes for three way calling and cancallforward.
Are you sure you are doing the right sequence of buttons.  If you have a
call coming in you must flash then * 0.  the flash button flashes the PBX
and * 0 flashes the CO.