Thank you all for your help, but I couldn't get this working so I went with an alternative method that works fine ...
Dim objOutlook As Outlook._Application = New Outlook.Application
Dim objNS As Outlook._NameSpace = objOutlook.Session
Dim objTasks As Outlook.MAPIFolder = objNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderTasks)
Dim objItems As Outlook._Items = objTasks.Items
Dim objTask As Outlook.TaskItem = DirectCast(objOutlook.CreateItem(Outlook.OlItemType.olTaskItem), Outlook.TaskItem)
Dim iCount As Int16 = objItems.Count
Dim i As Int16
Dim myTaskExists As Boolean = False
For i = 1 To iCount
If TypeOf (objItems.Item(i)) Is Outlook.TaskItem Then
If objItems.Item(i).Subject = myLeague & " Newsletter" Then
myTaskExists = True
End If
End If
Next
If myTaskExists = False Then
objTask.Status = Outlook.OlTaskStatus.olTaskInProgress
objTask.PercentComplete = 10
objTask.Importance = Outlook.OlImportance.olImportanceHigh
objTask.Categories = "Newsletters : In Progress"
objTask.Subject = myLeague & " Newsletter"
objTask.Save()
objTask = Nothing
End If