[Serusers] Windows Messenger 5.1 -> SER authentication fails

Hi all, I have a problem with using Windows Messenger 5.1, that is, I can't log in with SER 0.9.3. Everything is working OK with Xlite client. I try to set up my realm value to equal server name as it says in Admin guide for SER, but it doesn't help. If someone had similar problem and solve it, I would be very thankful if you can share solution with me. Thanks This is output from SER when trying to authenticate with WM. 0(22883) parse_headers: flags=-1 0(22883) check_via_address(192.168.0.101, 192.168.0.101, 0) 0(22883) DEBUG:destroy_avp_list: destroying list (nil) 0(22883) receive_msg: cleaning up 0(22883) SIP Request: 0(22883) method: <REGISTER> 0(22883) uri: <sip:debtest.stu.du> 0(22883) version: <SIP/2.0> 0(22883) parse_headers: flags=1 0(22883) end of header reached, state=5 0(22883) parse_headers: Via found, flags=1 0(22883) parse_headers: this is the first via 0(22883) After parse_msg... 0(22883) preparing to run routing scripts... 0(22883) parse_headers: flags=128 0(22883) DEBUG:maxfwd:is_maxfwd_present: value = 70 0(22883) DBG:maxfwd:process_maxfwd_header: value 70 decreased to 16 0(22883) parse_headers: flags=256 0(22883) end of header reached, state=9 0(22883) DEBUG: get_hdr_field: <To> [21]; uri=[sip:admin@debtest.stu.du] 0(22883) DEBUG: to body [<sip:admin@debtest.stu.du> ] 0(22883) get_hdr_field: cseq <CSeq>: <1> <REGISTER> 0(22883) DEBUG: get_hdr_body : content_length=0 0(22883) found end of header 0(22883) find_first_route: No Route headers found 0(22883) loose_route: There is no Route HF 0(22883) grep_sock_info - checking if host==us: 7==12 && [debtest.stu.du] == [161.53.0.131] 0(22883) grep_sock_info - checking if port 5060 matches port 5060 0(22883) grep_sock_info - checking if host==us: 7==12 && [debtest.stu.du] == [161.53.0.131] 0(22883) grep_sock_info - checking if port 5060 matches port 5060 0(22883) parse_headers: flags=-1 0(22883) check_via_address(192.168.0.101, 192.168.0.101, 0) 0(22883) parse_headers: flags=4096 0(22883) pre_auth(): Credentials with given realm not found 0(22883) build_auth_hf(): 'WWW-Authenticate: Digest realm="debtest.stu.du", nonce="43390f58ff776ef2b6700bd7e5cb53ea5b79453b" ' 0(22883) parse_headers: flags=-1 0(22883) check_via_address(192.168.0.101, 192.168.0.101, 0) 0(22883) DEBUG:destroy_avp_list: destroying list (nil) 0(22883) receive_msg: cleaning up