Error in sending Email Application

Hello all
I have written following code to send an email. but getting an error of
Message "Specified cast is not valid." String on the following line
SmtpMail.Send(ObjEmail)



Dim SmtpMail As SmtpMail
Dim ObjEmail As New MailMessage

SmtpMail.SmtpServer = "mail.suvana.com"
ObjEmail.BodyFormat = MailFormat.Text
ObjEmail.From = "[email protected]"
ObjEmail.Attachments.Add("C:\ajay1.pdf")
ObjEmail.To = "[email protected]"
'ObjEmail.Cc =
ObjEmail.Subject = "Test Mail From Infosys..."
ObjEmail.Body = " Hi this is Ajay"
SmtpMail.Send(ObjEmail)

SmtpMail = Nothing
ObjEmail = Nothing

ObjEmail.From = "[email protected]"

Its always the simplest errors that go through :D.