CDOSYS error: the send using configuration value is invalid

Hi all.

I use ASP page to send out email.
I use CDOSYS for that.
I run it at localhost.

However, I got this error "the send using configuration value is invalid" when I try it using Windows 2003. No problem trying it with Win XP.

Code:

---

<%
Set myMail=CreateObject("CDO.Message")
myMail.Subject="Sending email with CDO"
myMail.From="[email protected]"
myMail.To="[email protected]"
myMail.HTMLBody = "<h1>This is a message.</h1>"
myMail.Send
set myMail=nothing
%>

---

The error points to "myMail.Send".
Can somebody explain to me how to solve this problem?
Thanks in advance.