I reported this behavior earlier in a support ticket over two years ago but since it has not been addressed, I would try this approach. If an AreaSeries has the LineType set to LineTypes.Smooth, the graph series may become misleading or incorrect. Consider the attached screenshot (withoutsettings.png) showing a simple 10 point chart. Looking at the chart, you would assume that between 11:06 and 11:07, the response time was below 0. However the test values indicate that the values never were below 0. This makes the chart misleading and incorrect. It then makes the chart unreliable to the end user, thus unusable. The quick workaround is to set the LineType=straight but since you support a smooth linetype, it should be correct. Another, more serious, instance in the chart where (using smooth LineType) is where the series line will cross the x axis point (a timeline chart) more than 1 time which is actually a timeline chart violation. (attached file AreaSmooth2.png) .