Can't send email automatically outlook 2007

I want o send an email from excel but I have to open the outlook otherwise the mail is not sent. Why the command oEmail.Send doesn't work. Any idea?
Here is my code

Dim oApp As Outlook.Application
Dim oEmail As MailItem
Dim colAttach As Outlook.Attachments
Dim oAttach As Outlook.Attachment
    Set oApp = CreateObject("Outlook.Application")
    Set oEmail = oApp.CreateItem(olMailItem)
    oEmail.HTMLBody = "ola" & "<img src=""c:\senhora.jpg"" > " & vbNewLine
    oEmail.Save
    oEmail.Display
    oEmail.To = "myemail"
    oEmail.Subject = "Teste ao envio de email"
    oEmail.Send
    Set oEmail = Nothing
    Set colAttach = Nothing
    Set oAttach = Nothing
    Set oApp = Nothing