VBA doesn´t add datalabel

Question

I have an existent graph to which I added a macros. The macros should update the axes, add a datalabel to the last point and delete the datalabel of the previous point every time I update the database. However, the code doesn't recognize the last datalabel and doesn't add the next the first time I run the macros and shows error in the following line: ActiveChart.FullSeriesCollection(1).Points(ult2).DataLabel.Select I tried deleting that part and run the macros and add that for the second test. The datalabel is added but the third time it is not added again. I have run a test on another workbook and the macros runs perfectly on that. I hope someone can help me.

The full code is as follows:

Sheets(1).Select

 ult = Cells(Rows.Count, 1).End(xlUp).Row - 1
ult2 = ult - 1
Sheets(2).Select
ActiveSheet.ChartObjects("Gráfico 4").Activate
ActiveChart.Axes(xlCategory).Select
ActiveChart.Axes(xlCategory).MinimumScale = CDate(Sheets(1).Cells((ult - 23), 1).Value)
ActiveChart.Axes(xlCategory).MaximumScale = CDate(Sheets(1).Cells(ult + 1, 1).Value)

ActiveChart.FullSeriesCollection(1).Select
ActiveChart.FullSeriesCollection(1).Points(ult).Select
ActiveChart.FullSeriesCollection(1).Points(ult).ApplyDataLabels
ActiveChart.FullSeriesCollection(1).Points(ult2).DataLabel.Select
Selection.Delete
 ActiveSheet.ChartObjects("Gráfico 4").Activate
ActiveChart.FullSeriesCollection(1).Select
ActiveChart.FullSeriesCollection(1).Points(ult).Select
ActiveChart.FullSeriesCollection(1).Points(ult).ApplyDataLabels
ActiveChart.FullSeriesCollection(1).DataLabels.Select
ActiveSheet.ChartObjects("Gráfico 4").Activate
ActiveChart.FullSeriesCollection(1).DataLabels.Select
ActiveChart.FullSeriesCollection(1).Points(ult).DataLabel.Select
With Selection.Format.TextFrame2.TextRange.Font
    .NameComplexScript = "Humanst521 BT"
    .NameFarEast = "Humanst521 BT"
    .Name = "Humanst521 BT"
End With

Selection.Format.TextFrame2.TextRange.Font.Bold = msoTrue
With Selection.Format.TextFrame2.TextRange.Font.Fill
    .Visible = msoTrue
   .ForeColor.RGB = RGB(0, 32, 96)
    .ForeColor.TintAndShade = 0
    .ForeColor.Brightness = 0
    .Transparency = 0
    .Solid
End With
Selection.Format.TextFrame2.TextRange.Font.Size = 10
ActiveChart.SeriesCollection(1).DataLabels(ult).Format.TextFrame2.TextRange. _
    Characters.Text = ""
ActiveChart.SeriesCollection(1).DataLabels(ult).Format.TextFrame2.TextRange. _
    InsertChartField msoChartFieldValue, "", 1
With ActiveChart.SeriesCollection(1).DataLabels(ult).Format.TextFrame2.TextRange _
    .Font
    .Bold = msoTrue
    .Fill.Visible = msoTrue
    .Fill.ForeColor.RGB = RGB(0, 32, 96)
    .Fill.ForeColor.TintAndShade = 0
    .Fill.ForeColor.Brightness = 0
    .Fill.Transparency = 0
    .Fill.Solid
    .Size = 10
    .Name = "Humanst521 BT"
End With
With ActiveChart.SeriesCollection(1).DataLabels(ult).Format.TextFrame2.TextRange _
.ParagraphFormat
    .TextDirection = msoTextDirectionLeftToRight
    .Alignment = msoAlignCenter
End With

End Sub