[Serusers]Problem on ipv6

Hi, I can not enable ipv6 on ser. I have been set the following configuration on ser.cfg. listen=2001:238:202:0:230:1bff:feb8:32b9 listen=140.113.131.41 However, I found the following information on /var/log/message: Mar 9 20:10:09 TIPRA-41 ser: WARNING: fix_socket_list: could not rev. resolve 2001:238:202:0:230:1BFF:FEB8:32B9 Mar 9 20:10:09 TIPRA-41 ser: WARNING: fix_socket_list: could not rev. resolve 2001:238:202:0:230:1BFF:FEB8:32B9 I can't receive any 200 OK ,when I had been sent REGISTER using my UA(ipv6 enabled). The following is my "ifconfig" information: TIPRA-41:/home/rhliou # ifconfig eth1 Link encap:Ethernet HWaddr 00:30:1B:B8:32:B9 inet addr:140.113.131.41 Bcast:140.113.131.127 Mask:255.255.255.128 inet6 addr: 2001:238:202:0:230:1bff:feb8:32b9/64 Scope:Global inet6 addr: fe80::230:1bff:feb8:32b9/64 Scope:Link UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1785125 errors:0 dropped:0 overruns:0 frame:0 TX packets:20517 errors:0 dropped:0 overruns:0 carrier:0 collisions:759 txqueuelen:1000 RX bytes:158891946 (151.5 Mb) TX bytes:3155181 (3.0 Mb) Interrupt:169 Base address:0xc000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:568 errors:0 dropped:0 overruns:0 frame:0 TX packets:568 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:269972 (263.6 Kb) TX bytes:269972 (263.6 Kb) Thanks in advance Best regards, Ren-Huang Liou