[Serusers] Some problem about too many hops

Dear ser users, Originally, I have a ser worked correctly for me. We also implemented the www authentigation function. But when we change our domain name, the server can't work properly. We encountered the following strange stuation: We clear the mysql database, but users from the original database can login with proper username and password. The users now can login. But each time they make a call, ser send 200 OK directly to my client SJphone without asking the receiver. So ACK sent by the caller can't reach the receiver. My ser always sends 483 too many hops :( I'm really messed about such strange things. Hope that someone would be kind enough to give some hints. Sincerely, Kun