I'm plotting data in a time series (hour by hour) for every day of the year. I'm using a logarithmic scale to show the varying detail from a value of 10 to a value of 1 billion. In each hour, there are multiple data series. Since I need to show data for each hour in the data, my x-axis reflects the time (by hour) whether there is data or not. The weird thing that happens is when there is null data for a given series/hour, it makes a plot on the graph (it only does this when the columns are stacked). If I hover over the bars, they still say value="", so I'm not sure why they show up. Any thoughts?