Chart sheets do not have a cells property.
try this revised code
bool2 = True
If Cells(counter2, 1) <> Cells(counter2 + 1, 1) Then
bool2 = False
Sheets("Chart").Select
ActiveChart.SeriesCollection.NewSeries
With ActiveChart.SeriesCollection.NewSeries
.Name = Sheets("Temporary").Cells(position2, 1)
.Values = Sheets("Temporary").Range(Sheets("Temporary").Cells(6, position2), Sheets("Temporary").Cells(6, counter2))
.XValues = Sheets("Temporary").Range("A4:A14")
End With
Sheets("Temporary").Select
End If
Next
Sheets("Chart").Select
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