Using Excel 2007, is it possible to change the transparency of chart grid lines using VBA or VB.NET? I have the following code, which throws an exception on the last line: Dim axis As Excel.Axis = chart.Axes(Excel.XlAxisType.xlCategory) axis.HasMajorGridlines = True axis.MajorGridlines.Border.Color = Color.Gray.ToArgb axis.MajorGridlines.Border.LineStyle = Excel.XlLineStyle.xlContinuous axis.MajorGridlines.Format.Fill.Transparency = 0.8 ( Of course, this code is in VB.NET ) Thanks!