Excel中的散点图通过vb.net从不相邻的列

Question

I'm trying to draw charts in an excel spreadsheet through a vb.net code. I want to draw a scatter chart from column A (X-axis) and column D (Y-axis). With some online help, I have written this code so far:

Dim xlApp As Excel.Application
Dim xlWorkBook As Excel.Workbook
Dim xlWorkSheet As Excel.Worksheet
xlApp = New Excel.Application

xlWorkBook = xlApp.Workbooks.Open("C:\excel_file.xlsx")

    xlApp.Visible = True

    xlWorkSheet = xlWorkBook.Sheets("Foglio4")

    With xlWorkSheet

        .Shapes.AddChart.Select()

        With xlApp.ActiveChart

            .ApplyCustomType(Excel.XlChartType.xlXYScatterSmoothNoMarkers)

            xlApp.ActiveChart.SeriesCollection(1).Name = "X-Y"
            xlApp.ActiveChart.SeriesCollection(1).XValues = "='Foglio4'!$A$2:$A$1446"
            xlApp.ActiveChart.SeriesCollection(1).Values = "='Foglio4'!$D$2:$D$1446"

        End with

    End with

But I get a chart with the series I want together with other four series, made with the A-column on the X-axis and all the others on the Y-axis, as I have five columns.

Why does it draw all those series? Any idea?

Answer 1

Thanks to the precious comment made by Tim Williams, I've added this part to my code:

[...]

xlApp.ActiveChart.SeriesCollection(1).Name = "X-Y"
xlApp.ActiveChart.SeriesCollection(1).XValues = "='Foglio4'!$A$2:$A$1446"
xlApp.ActiveChart.SeriesCollection(1).Values = "='Foglio4'!$D$2:$D$1446"

For n = .SeriesCollection.Count To 2 Step -1
    .SeriesCollection(n).Delete
Next n

[...]

This deletes all the unwanted series leaving just the one wanted, that is the #1.