1004 error

[Boogerbut74]

Hello im getting a error where it says Set GraphRange = ActiveSheet.Range("D10:" & rng & lastrow)
i was messing around trying to fix it and i kept breaking it more

    Dim lastrow As Integer
    Dim GraphRange As Range
    Dim rng As Range
    
    Set rng = ActiveWorkbook.Worksheets("Reference").Range("H39")
    
    
    
    lastrow = ActiveSheet.Cells(ActiveSheet.Rows.Count, 10).End(xlUp).Row
    
    'set chart data range (including series names)
    Set GraphRange = ActiveSheet.Range("D10:" & rng & lastrow)
    
    'Create a chart
    Set cht = ActiveSheet.ChartObjects.Add( _
    Left:=ActiveCell.Left, _
    Width:=450, _
    Top:=ActiveCell.Top, _
    Height:=250)
    
    'Give chart some data
    cht.Chart.SetSourceData Source:=GraphRange

    
    
    'Determine the chart type
    cht.Chart.ChartType = xlXYScatterSmooth
    'edits chart detailes
    cht.Chart.Axes(xlCategory).MinimumScale = 0
    cht.Chart.Axes(xlCategory).MaximumScale = 100
    
    cht.Chart.Axes(xlValue).MinimumScale = 115
    cht.Chart.Axes(xlValue).MaximumScale = 140
    
    cht.Chart.Legend.Position = xlLegendPositionBottom
 
    cht.Select
ActiveChart.FullSeriesCollection(1).Delete

 

[Joe4]

What is in cell H39 on your Reference sheet?
What value is your "lastrow" calculation returning?