asterisk users - Sep 2011 - I can't figure out how to redirect a call to a trunk.

OK, i am hoping that someone will be able to help me out.
I am using FreePBX 2.8.1.4

I have two asterisk servers connected with a iax trunk.
The trunk is working fine when used via the outbound route setting.
meaning an extension on one server can call a specific extension on
the other server.

now what i want to do is set it up so that an incoming call (from a
third server)
is redirected to the second server from the first server when the
extension number does exist on the first server.
I thought I knew how to do this.... setup an inbound route that
answers any inbouond call and set the desitnation
to be "trunk" "server2"

but this doesn't seem to be working.
I know the inbound route is being called, i can even see the first
server trying to forward the call to server 2.
but the problem seems to be that no $OUTNUM is being set, so no
extension number on the second server is specified...
at which point the call fails.  I get an "all circuits are busy now"
announcement.

i upgraded to freepbx 2.8.x.x because of the fact that "FOLLOWME" and
"INBOUND ROUTES" were both able to specify a trunk
as a desitnation... but neither are working for me now?

am i doing something wrong?

-- 
Tomoki Taniguchi