Adding new series to a graph automatically - excel

Question

I'm trying to create a dynamic Scatterchart in the worksheet("Graphs") using a button.
The Seriesname has to be equal to Worksheets("VS_P240_X").Cells(1,i), where i is a counter for the columns.
The XValues have to be equal to Worksheets("VS_P240_X").Range(cells(3,i).cells(1000,i)).
The YValues have to be equal to Worksheets("VS_P240_Y").Range(cells(3,i).cells(1000,i)).
When I Update the workbook the counter i will change, and I want that the chart will automatically update with the new series. I wrote this code but it is not working, do you have some suggestions?
Private Sub CommandButton5_Click()
'Graph generation NON COMPLETO
Dim i As Integer
Dim Chart1 As Chart
Set Chart1 = Sheets("Graphs").ChartObjects("Chart 1").Chart
For i = 1 To Lastcolumn
With Chart1
.ChartType = xlXYScatter
.SeriesCollection.NewSeries
'Change to what your series should be called
.SeriesCollection(i).Name = Worksheets("VS_P240_X").Cells(1, i).Value
.SeriesCollection(i).XValues = Worksheets("VS_P240_X").Range(Cells(3, i), Cells(1000, i))
.SeriesCollection(i).Values = Worksheets("VS_P240_Y").Range(Cells(3, i), Cells(1000, i))
End With
Next i
End Sub

Answer 1

To avoid confusion/bugs, it's best to specify a worksheet every time you use Range or Cells()
Something like this should work:
Private Sub CommandButton5_Click()
Dim i As Long, Lastcolumn As Long 'use long not integer
Dim Chart1 As Chart, wsX As Worksheet, wsY As Worksheet
Set wsX = Worksheets("VS_P240_X")
Set wsY = Worksheets("VS_P240_Y")
Set Chart1 = Sheets("Graphs").ChartObjects("Chart 1").Chart
Do While Chart1.SeriesCollection.Count > 0 'remove any existing data
Chart1.SeriesCollection(1).Delete
Loop
Chart1.ChartType = xlXYScatter 'do this outside of the loop...
Lastcolumn = wsX.Cells(1, wsX.Columns.Count).End(xlToLeft).Column
For i = 1 To Lastcolumn
With Chart1.SeriesCollection.NewSeries
.Name = wsX.Cells(1, i).Value
.XValues = wsX.Range(wsX.Cells(3, i), wsX.Cells(1000, i))
.Values = wsY.Range(wsY.Cells(3, i), wsY.Cells(1000, i))
End With
Next i
End Sub