Returns a ChLine object that you can use to change the appearance of the specified chart element.
expression.Line
expression Required. An expression that returns one of the objects in the Applies To list.
When used with other properties, the Line property can format axes, trendlines, lines on line or stock charts, error bars, and gridlines.
This example sets the line color for the specified series.
ChartSpace1.Charts(0).SeriesCollection(0).Line.Color = "red"