Here's a technique for adding data labels that show up kind of like
tooltips. If you left-click and hold on a point it shows the data
label, then when you release the data label disappears. If you right-
click then the data label stays there (because the context menu
apparently interrupts the mouse-up event chain) and you can left click
to make it go away.

I've got the following in a sheet module (BTW, my chart uses dynamic
ranges that address parts of a pivottable. I do it this way, because
my chart x-axis is a date type and I want a natural spacing so I can't
use a pivotchart (which would use equal spacing for each date
'category')).

-----------shtXYZ
Option Explicit

Private my_labeller As PointDblClickLabeller

Private Sub Worksheet_PivotTableUpdate(ByVal Target As PivotTable)
   Application.EnableEvents = False
   Me.Calculate
   Set my_labeller = New PointDblClickLabeller
   my_labeller.init Me.ChartObjects(1).Chart,
flatten_array(Me.Range("PvtLabels").Value)
   Application.EnableEvents = True
End Sub

Private Function flatten_array(data As Variant) As Variant
   Dim i As Long, v As Variant
   ReDim result(1 To 1)

   i = UBound(result)
   For Each v In data
       If i <> UBound(result) Then
           ReDim Preserve result(1 To UBound(result) + 1)
       End If
       result(i) = v
       i = i + 1
   Next

   flatten_array = result
End Function

---------Class PointDblClickLabeller
Option Explicit

Private WithEvents mChart As Excel.Chart

Private labels As Variant

Public Sub init(a_chart As Excel.Chart, some_labels As Variant)
   Set mChart = a_chart
   labels = some_labels
End Sub

Private Sub mChart_MouseDown(ByVal Button As Long, _
       ByVal Shift As Long, ByVal x As Long, ByVal y As Long)
   Dim elementId As Long, arg1 As Long, arg2 As Long
   mChart.GetChartElement x, y, elementId, arg1, arg2
   If elementId = xlSeries Then
       If arg2 <= UBound(labels) Then
           With mChart.SeriesCollection(arg1).Points(arg2)
               Application.ScreenUpdating = False
               .HasDataLabel = True
               .DataLabel.Font.Size = 8
               .DataLabel.Text = labels(arg2)
               .DataLabel.Border.Weight = xlHairline
               .DataLabel.Shadow = True
               .DataLabel.Interior.Color = 13434879
               .DataLabel.Position = xlLabelPositionAbove
               Application.ScreenUpdating = True
           End With
       End If
   End If
End Sub

Private Sub mChart_MouseUp(ByVal Button As Long, _
       ByVal Shift As Long, ByVal x As Long, ByVal y As Long)
   Dim elementId As Long, arg1 As Long, arg2 As Long
   mChart.GetChartElement x, y, elementId, arg1, arg2
   If elementId = xlSeries Then
       With mChart.SeriesCollection(arg1).Points(arg2)
           If .HasDataLabel Then
               .DataLabel.Text = ""
               .HasDataLabel = False
           End If
       End With
   End If
End Sub

That worked! Thanks