ASP.NET MS chart control: Data points insertion error. Only 2 Y values can be set for this data series. Parameter name: dataSource

I'm getting this error on my MS Chart control:

Data points insertion error. Only 2 Y values can be set for this data series. Parameter name: dataSource

It occurs on line chartPriceHistory_STATIC.DataBind() in my code below.

I think it has got something to do with the way I'm adding points (AddXY) but can't figure out what it is.

I tried these 2 code options:

Option 1 chartPriceHistory_STATIC.Series(seriesName).Points.AddXY(get3LetterMonth(CDate(row("createdate")).Month) + "-" + CDate(row("createdate")).Year.ToString, {CType(row("price"), Integer), totalobjects})

Option 2 chartPriceHistory_STATIC.Series(seriesName).Points.AddXY(get3LetterMonth(CDate(row("createdate")).Month) + "-" + CDate(row("createdate")).Year.ToString, CType(row("price"), Integer))
chartPriceHistory_STATIC.Series("totalobjects").Points.AddXY(get3LetterMonth(CDate(row("createdate")).Month) + "-" + CDate(row("createdate")).Year.ToString, totalobjects)

Both throw the same error...what am I missing?

    Dim mycommand As New SqlCommand("SELECT avgprice, createdate, totalobjects FROM avgprices", myConnection)
    Dim dtPrices As New System.Data.DataTable
    dtPrices.Columns.Add("price", System.Type.GetType("System.Int32"))
    dtPrices.Columns.Add("createdate", System.Type.GetType("System.DateTime"))
    dtPrices.Columns.Add("totalobjects", System.Type.GetType("System.Int32"))

    Dim dr As System.Data.DataRow

    Try
        Dim reader As SqlDataReader = mycommand.ExecuteReader()
        While reader.Read
            dr = dtPrices.NewRow()
            dr("price") = reader("price")
            dr("createdate") = reader("createdate")
            dr("totalobjects") = reader("totalobjects")
            dtPrices.Rows.Add(dr)
        End While
    Catch ex As Exception
    End Try

    ' Initializes a New instance of the DataSet class
    Dim myDataSet As DataSet = New DataSet()

    'Adds rows in the DataSet
    myDataSet.Tables.Add(dtPrices)

    chartPriceHistory_STATIC.Series.Clear()

    Dim seriesName As String = "Avg price"
    chartPriceHistory_STATIC.Series.Add(seriesName)
    chartPriceHistory_STATIC.Series(seriesName).XValueMember = "Date"

    chartPriceHistory_STATIC.ChartAreas.Add("ChartArea1")

    chartPriceHistory_STATIC.Series(seriesName).YValuesPerPoint = 2

    chartPriceHistory_STATIC.ChartAreas(0).AxisY.MajorGrid.Enabled = True
    chartPriceHistory_STATIC.ChartAreas(0).AxisY.Title = "Price"

    Dim totalobjects As Integer = 1


    chartPriceHistory_STATIC.Series.Add("Series2")
    chartPriceHistory_STATIC.Series("Series2").YAxisType = AxisType.Secondary
    chartPriceHistory_STATIC.Series("Series2").XValueMember = "Date"
    chartPriceHistory_STATIC.Series("Series2").YValueMembers = "totalobjects"
    chartPriceHistory_STATIC.Series("Series2").Name = "totalobjects"
    chartPriceHistory_STATIC.Series("totalobjects").ChartType = SeriesChartType.Line
    chartPriceHistory_STATIC.Series("totalobjects").ToolTip = "Total objects"


    chartPriceHistory_STATIC.Series(0).YAxisType = AxisType.Primary
    chartPriceHistory_STATIC.Series(1).YAxisType = AxisType.Secondary


    For Each row As DataRow In myDataSet.Tables(0).Rows
        totalobjects += 1

        'I tried: these 2 options, both generate the same error
        chartPriceHistory_STATIC.Series(seriesName).Points.AddXY(get3LetterMonth(CDate(row("createdate")).Month) + "-" + CDate(row("createdate")).Year.ToString, {CType(row("price"), Integer), totalobjects})

        chartPriceHistory_STATIC.Series(seriesName).Points.AddXY(get3LetterMonth(CDate(row("createdate")).Month) + "-" + CDate(row("createdate")).Year.ToString, CType(row("price"), Integer))
        chartPriceHistory_STATIC.Series("totalobjects").Points.AddXY(get3LetterMonth(CDate(row("createdate")).Month) + "-" + CDate(row("createdate")).Year.ToString, totalobjects)
    Next

    chartPriceHistory_STATIC.DataSource = myDataSet
    chartPriceHistory_STATIC.DataBind()

You need to set the YValueMembers for the "Avg price" series, too.

Add this line (use whatever string you want to plot on Y axis):

chartPriceHistory_Static.Series(seriesName).YValueMembers = "totalobjects"

Add it just before this line:

chartPriceHistory_Static.Series(seriesName).YValuesPerPoint = 2

Also, your name of date/createdate column is inconsistent - you won't see the plots until you correct that.

If you are only adding 1 YValue, you can reduce the YValuesPerPoint down to 1 again, without error.

Tested. Works fine. Cheers!