[SR-Users] BYE request with Sipp refused

Hello everyone, I'm a newbie in kamailio world and make some tests to dispatch call over several asterisk instances. This part works, my call has been distributed over two instances (if i make a call with jitsi for example). Now, i want to test performance of my cluster and use Sipp to chalenge it. All method is working fine, except the BYE method, where kamailio send me back a 404 Not here. This is my SIPP scenario: ... <pause/> <!-- The 'crlf' option inserts a blank line in the statistics report. --> <send retrans="500"> <![CDATA[ BYE sip:[service]@[remote_ip] SIP/2.0 Via: SIP/2.0/[transport] [local_ip]:[local_port];branch=[branch] From: sipp <sip:sipp@loicchabert.fr>;tag=[pid]SIPpTag00[call_number] To: sut <sip:[service]@[remote_ip]:[remote_port]>[peer_tag_param] Call-ID: [call_id] CSeq: 2 BYE Contact: sip:sipp@[local_ip]:[local_port] Max-Forwards: 70 Subject: Performance Test Content-Length: 0 ]]> </send> ... I use the classic file of kamailio, with some adjustement for dispatching. Any ideas concerning this problem ? This BYE is not in transaction so he is drop by kamailio ? Thank in advance, Regards.