Audio only one side for outgoing call

Friends,

I have recently upgraded from asterisk 1.2 to 1.4. I am using an analog Digium 24 port TDM2400P for making outgoing calls. Every thing was working before, but after upgrade I am not getting audio from the other end. The person who I call can hear my voice but I cant hear him, even ringing is not heard. Only blank. What could be the problem. Somebody pls help me.
My zapata.conf :

[channels]
language=en
context=outgoing
signalling=fxs_ks
busysignalling=yes
busydetect=yes
busycount=6
group=1
channel=>1-8

and zaptel.conf is:
fxsks=1-24
loadzone=us
defaultzone=us

Only 8 analog lines are connected to the card.

Please help.

Thanks & Regards
Shanavaz.