I am building several line charts dynamically via VBA, and each chart has multiple lines. Since I don't know how many lines a chart would have, I use the xlColorIndexAutomatic value for xlColorIndex property of the lines. The problem I ran into is that Excel would automatically generate yellow lines against a white background, making these lines difficult to see. Is there a way to modify, or validate the color index values generated by xlColorIndexAutomatic so that lighter colors, such as yellow, would not be used against a white background? I tried to read and validate the colorindex property of each series object, but it seems that they are aways equal to -4105 once xlColorIndexAutomatic was assigned to a series, e.g., all colored lines would have -4105 as their color index value.