When possible, set the filterData property to false. In the transformation from data to screen coordinates, the various series types filter the incoming data to remove any missing values that are outside the range of the chart; missing values would render incorrectly if drawn to the screen. For example, a chart that represents vacation time for each week in 2003 might not have a value for the July fourth weekend because the company was closed. If you know your data model will not have any missing values at run time, or values that fall outside the chart's data range, you can instruct a series to explicitly skip the filtering step by setting its filterData property to false.