Categorizing emails based on the subject

[Ludo]

I copy pasted it at the top of the ThisOutlookSession.
the error message is gone now, but it still doesn't run automatically...

Regarding the attachement, this portion of code can be part of my main code?
Like:

Public Sub autocategories()
Dim olItem As Object
    For Each olItem In Application.ActiveExplorer.Selection
        If InStr(1, olItem.Subject, "[cat1]", vbTextCompare) > 0 Then
            olItem.Categories = "CAT1"
        ElseIf InStr(1, olItem.Subject, "[cat2]", vbTextCompare) > 0 Then
           olItem.Categories = "CAT2"
           For i = 1 To olItem.Attachments.Count
               If InStr(1, olItem.Attachments(i).fileName, "[CAT1]", vbTextCompare) > 0 Then
                   olItem.Categories = "CAT1"
                   olItem.Save
                   Exit For
               End If
          Next i
         olItem.Save
    Next olItem
    Set olItem = Nothing
End Sub

Or should it be part of a different macro?