Script to accept meeting invitations from specified senders

I'm attempting to use this code to automatically accept meeting invitations from specific senders:

Code:

---

Private Sub Application_Startup()
Set GItems = Outlook.Application.Session.GetDefaultFolder(olFolderInbox).Items
End Sub

Private Sub GItems_ItemAdd(ByVal Item As Object)
Dim xMtRequest As MeetingItem
Dim xAppointmentItem As AppointmentItem
Dim xMtResponse As MeetingItem
If Item.Class = olMeetingRequest Then
    Set xMtRequest = Item
    Set xAppointmentItem = xMtRequest.GetAssociatedAppointment(True)
    If xAppointmentItem.GetOrganizer.Name = "SENDER NAME" Then
        Set xMtResponse = xAppointmentItem.Respond(olResponseAccepted, True)
        xMtResponse.Send
        xMtRequest.Delete
    End If
End If
End Sub

---

xMtResponse is always "nothing", so the xMtResponse.Send fails with "Object variable or With block variable not set".

What am I doing wrong?