Thank you so much, Franz! Indeed, the problem is coming from xml. It is well-formed but seems the server can't understand it. The whole xml document I used is the similar with yours except the root element with namespace which is showing below: <cr: ruleset xmlns="urn:ietf:params:xml:ns:common-policy" xmlns:pr="urn:ietf:params:xml:ns:pres-rules" xmlns:cr="urn:ietf:params:xml:ns:common-policy"> I got no error sending the xml doc with this as beginning. Only no Notify message after updating Publish, and sometimes the first Subscribe can't get through that is no Notify sending back from server. It's really weired! Anyway, I finally fix it with your advise, Thanks Indeed. Kevin, _________________________________________________________________ 手机也能上 MSN 聊天了，快来试试吧！ http://mobile.msn.com.cn/