[Serusers] About avp_db_store()

Hi all, I am trying to use avp_db_store() stores my table "contact" with caller uri ex: table name: contact ----------------------------- | username | domain | ----------------------------- | | | ----------------------------- | | | ----------------------------- If (method=="INVITE"){ avp_write("$ruri/username", "s:name"); avp_db_store("$ruri", "s:name/contact"); }; if the incoming call then save username and domain of caller in contact caller: bob(a)iptel.org => ----------------------------- | username | domain | ----------------------------- | bob | iptel.org | ----------------------------- | | | ----------------------------- but not success, system reply ERROR:avpops:db_store: insert faild Please help me in the problem Thanks a lot in advance chungyu