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

Hi Ross
got error in outlook 2007, in instruction send
Here is the error
Application-defined or object-defined error
This code works in outlook 2007

Shell "outlook.exe", vbMinimizedFocus
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
    
'MsgBox "terminei"
Set oEmail = Nothing
    Set colAttach = Nothing
    Set oAttach = Nothing
    Set oApp = Nothing
Shell "taskkill /F /IM outlook.exe", vbHide

But I don't like it because I have to open outlook and kill the process.
Any ideas?