[SR-Users] $rs printed null

Hi community, So I'm running 4.1.5 Kam version and I wanted to print out $rs variable. It printed out <null> right after the 183 session. Should it print something? What our server side sent is this: INVITE 100 183 488 or 487 And this is the output in kam logs: Jun 28 15:05:49 sjomainfnsg51 /usr/local/sbin/*kamailio*[15215]: INFO: <script>: [4975Fz-ses1-414b02f5R68422169(a)192.168.0.22][2][CSeq 1] fuze_for_mac/99.99.99999 Reply status <null> detected... any thoughts? Thanks -- Andy Chen -- *Confidentiality Notice: The information contained in this e-mail and any attachments may be confidential. If you are not an intended recipient, you are hereby notified that any dissemination, distribution or copying of this e-mail is strictly prohibited. If you have received this e-mail in error, please notify the sender and permanently delete the e-mail and any attachments immediately. You should not retain, copy or use this e-mail or any attachment for any purpose, nor disclose all or any part of the contents to any other person. Thank you.*