asterisk users - Mar 2005 - 'RFC3261 transaction matching failed' and 'one-way' communication

Forwarding a call from Asterisk to Microsoft Live Communication Server 2005 
via SER (to translate from UDP to TCP), I get a 'one-way' communication 
(WMessenger user can hear voice but PSTN phone user cannot).

Running SER in debug mode, I found:

 DEBUG: RFC3261 transaction matching failed

 DEBUG: t_lookup_request: no transaction found

Searching Google, I found that this is a known bug in Asterisk (2687):

 http://bugs.digium.com/bug_view_page.php?bug_id=0002687

I upgraded to 1.0.7 (Debian unstable) but bug is still present.

Do I need to compile from CVS? Some other chance? I'm not a compile guru...



Thanks in advance

Domenico Viggiani