EPPlus条形图条在Excel 2013中不显示负值的颜色，但在Excel 2007中工作正常

I am using a BarClustered chart using EPPlus for Excel Package in C#. I am able to generate the bar chart as required. Only problem I am facing is that when I have a negative value, the bar does not show any color. It would be as if a transparent bar with only the border.I am using a BarClustered chart using EPPlus fo