Series.XValues (Excel)

Returns or sets an array of x values for a chart series. The XValues property can be set to a range on a worksheet or to an array of values, but it cannot be a combination of both.

For PivotChart reports, this property is read-only.

Charts("Chart1").SeriesCollection(1).XValues = _ 
 Worksheets("Sheet1").Range("B1:B5")