SMTPMAIL - Error: SendUsing configuration is not valid

I am trying to send a simple email:
I

<%@dotnet.itags.org. Page Language="VB" %>
<%@dotnet.itags.org. import Namespace="System.Data.SqlClient" %>
<%@dotnet.itags.org. import Namespace="System.Web.Mail" %>
 <script runat="server">
 Sub SubmitBtn_Click(ByVal sender As Object, ByVal e As ImageClickEventArgs)
smtpmail.send("bjlappin@dotnet.itags.org.maine.rr.com", "dlappin@dotnet.itags.org.maine.rr.com", "Testing Mail", "xxxxxxxxxxx")
 End Sub
</script>
I get this error:
Exception Details: System.Runtime.InteropServices.COMException: The "SendUsing" configuration value is invalid.

Add SmtpMail.SmtpServer = "Localhost"
thanks!