In the BeforeUpdate event procedure of the control in which the requested date is entered put code along these lines:
Const MESSAGE_TEXT = Cut off date for the roster has been passed."
Dim dtmCutOfDate As Date
Dim strCriteria As String
Dim ctrl As Control
Set ctrl = Me.ActiveControl
If Not IsNull(ctrl) Then
strCriteria = "#" & Format(ctrl,"yyyy-mm-dd") & "# Between RosterStart And RosterFinish"
dtmCutOffDate = DLookup("CutOffDate", "Rosters", strCriteria)
If dtmCutOffDate < VBA.Date Then
MsgBox MESSAGE_TEXT, vbExclamation, "Invalid Operation"
Cancel = True
End If
End If
Ken Sheridan, Stafford, England