[Serusers] Unresolvable Destination

Hi, I'm using Presence Snapshot 4.1. If I want to REGISTER my client, I get the error: Unresolvable Destination. I have following lines in my log message: /usr/sbin/ser[8941]: Unknown domain to: sip:PDA_User@fh-joanneum.at from: sip:PDA_User@fh-joanneum.at /usr/sbin/ser[8941]: ERROR: mk_proxy: could not resolve hostname: "fhjoanneum.at" /usr/sbin/ser[8941]: ERROR: uri2proxy: bad host name in URI <sip:PDA_User@fhjoanneum.at> /usr/sbin/ser[8941]: ERROR: t_forward_nonack: failure to add branches /usr/sbin/ser[8941]: sl_reply error() /usr/sbin/ser[8941]: ERROR: sl_reply_error used: I'm terribly sorry, server error occurred (1/SL) U 10.0.0.3:5060 -> 10.0.0.11:5060 REGISTER sip:PDA_User@fh-joanneum.at SIP/2.0..Via: SIP/2.0/UDP 10.0.0.3:5060;branch=z9hG4bK479720758..Max-Forwards: 70..From: <sip:PDA_User@fhjoanneu m.at>;tag=1505826169..To: <sip:PDA_User@fh-joanneum.at>..Call-ID: 927318080- 406265317-1110482780..CSeq: 1 REGISTER..Contact: <sip:PDA_User@10.0.0.3>.. Content-Length: 0..User-Agent: SIP .NET 1.0 evaluation version, www.independentsoft.com.... # U 10.0.0.11:5060 -> 10.0.0.3:5060 SIP/2.0 478 Unresolvable destination (478/TM)..Via: SIP/2.0/UDP 10.0.0.3:5060;branch=z9hG4bK479720758..From: <sip:PDA_User@fhjoanneum. at>;tag=1505826 169..To: <sip:PDA_User@fh-joanneum.at>;tag=589230a54cd08b3768529724501fae28- 2449..Call-ID: 927318080-406265317-1110482780..CSeq: 1 REGISTER..Server: S ip EXpress router (0.10.99-dev35-pa-4.1 (i386/linux))..Content-Length: 0..Warning: 392 10.0.0.11:5060 "Noisy feedback tells: pid=8941 req_src_ip=10.0 .0.3 req_src_port=5060 in_uri=sip:PDA_User@fh-joanneum.at out_uri=sip:PDA_User@fh-joanneum.at via_cnt==1".... # U 10.0.0.11:5060 -> 10.0.0.3:5060 SIP/2.0 500 I'm terribly sorry, server error occurred (1/SL)..Via: SIP/2.0/UDP 10.0.0.3:5060;branch=z9hG4bK479720758..From: <sip:PDA_User@fh-joanneum. at>;tag=1505826169..To: <sip:PDA_User@fhjoanneum. at>;tag=56a704c9068c5b1b9228b761fe5fb2cc.2449..Call-ID: 927318080- 406265317-1110482780..CSeq: 1 REGI STER..Server: Sip EXpress router (0.10.99-dev35-pa-4.1 (i386/linux))..Content- Length: 0..Warning: 392 10.0.0.11:5060 "Noisy feedback tells: pid=8941 req_src_ip=10.0.0.3 req_src_port=5060 in_uri=sip:PDA_User@fh-joanneum.at out_uri=sip:PDA_User@fh-joanneum.at via_cnt==1" I hope you can help me. Regards, Alois