Display bar charts in ArcMap

I am trying to symbolize data as bar charts in ArcMap. I have a feature class with two sets of data, and I want the bar charts next to each other on the map. The problem I am having is that the map will only display the bars if both sets of data are not Null. Is there a way to display all the bars with data? If I put 0 for the Nulls, then a flat bar appears, and I don't want that either.