I set duplicate_uri to store sip messages in an external server

#!ifdef WITH_SIPTRACE
modparam("siptrace", "db_url", mysql_conn_data)
modparam("siptrace", "traced_user_avp", "$avp(s:traced_user)")
modparam("siptrace", "trace_on",1) # disable siptrace
modparam("siptrace", "trace_flag",FLT_SIPTRACE)
modparam("siptrace", "trace_to_database", 0)
modparam("siptrace", "duplicate_uri", "sip:siptracesrv:6060")
#!endif

but most of the time I get those error messages in log files when kamailio tries to send the message out

/usr/local/sbin/kamailio[11946]: ERROR: <core> [forward.c:220]: get_out_socket(): ERROR: get_out_socket: no socket found
/usr/local/sbin/kamailio[11946]: ERROR: siptrace [siptrace.c:1487]: trace_send_duplicate(): can't forward to af 2, proto 1 no corresponding listening socket

Do you have any ideas?

Thanks for your help,