[Serusers] Please help with my questions !

Dear all !! Here I have some questions in using the SER to configure my network environment. First,I would ask you how to do the registration process from the UA to SER. I have used serctl script to add some user account along with password and email in my database(mysql) What I have done is like that "serctl add bob 12345 bob@IP address [my server's IP address(public)] After that,when I keyin "mysql" and enter the ser database,I can see the user account what I add just exist. Then, I try to use the "SipSet" which is a user agent developed and provided by "vovida.org" to set some configuration parameters which include User Name , Password, SIP Proxy Server,etc in order to make a phone call to other users, but it seems I can't logon my ser which can be observed by using "serctl monitor" showing failures and "SipSet" user agent log file. In this log file,it says that the UA can't find the the registration server and try again to proxy server instead which is still can't be found. But I feel so strange that the "serctl monitor" showing the ser is on although have some failures messages received from UA. So,why the UA's log file says that the server can't find ser? So,according to the above description and problems. I would like to ask some questions to all and would be grateful for your help. 1.Can I use "SipSet" user agent as the UA to make calls from one to another through ser? Have any one used "SipSet" before. 2.How to do registration process from UA to ser? Also,what I have configured ser to manage user account and password above to let UA registers to ser is correct? If it is wrong,please tell me how to use serctl script to manage registration process? Or I just must need serweb to manage registration process? And how to change ser proxy mode to registrator mode and also inversely? 3. Can I let the SIP URL to be the format as username@IP address ? Or I must set it as username@domain name ^^^^^^^^^^^^^^ <------ like "iptel.org" 4. I have thought that is it the database I have created have some problems?? Can somebody tell me what the relationship between mysql and ser-mysql?? PS. I have installed packages "mysql , mysql-bench, mysql-client, mysql-devel, mysql-shared" and ser-mysql from iptel.org's web in my machine. I will be grateful for your reply and help. Thank you all very much !! Best regards !!