asterisk users - Apr 2008 - Version FIOS MWI Detection - asterisk-1.6-beta7

I'm trying to get the Telco MWI recognition working in asterisk-1.6-beta7. 
I'm told that it's supposed to work provided
my telco support FSK MWI signalling.

I have Verzon FIOS.  I believe I have FSK MWI signaling as I can hear the
standard stutter tone when I pick up a live
handset in front of my asterisk connection.

I have the Verizon line attached to a TDM400 card, port 4.

I have these in my zapata.conf file:

; PSTN connected here
;immediate=no
;busydetect=yes
;busycount=8
;musiconhold=default
mwimonitor=yes
mwilevel=256
mwimonitornotify=/usr/local/sbin/zapnotify.sh
faxdetect=incoming
signalling=fxs_ks
context=incoming
channel => 4

Does anyone have this feature working?

Do you see anything wrong with my configuration?

Thanks,

Jim