Option Explicit
Private Sub Worksheet_SelectionChange(ByVal Target As Range)

    Dim Cancel As Boolean
    Dim DateFormats, DF
    DateFormats = Array("m/d/yyyy", "dd mmmm yyyy")
    On Error GoTo fim
If Target.Value = "" Then
 
    For Each DF In DateFormats
    
        If DF = Target.NumberFormat Then
            If CalendarFrm.HelpLabel.Caption <> "" Then
                CalendarFrm.Height = 191 + CalendarFrm.HelpLabel.Height
            Else: CalendarFrm.Height = 191
                CalendarFrm.Show
                Cancel = True
            End If
        End If
    
    Next
    
End If
fim:
End Sub