Vishal Composer Chart interpret blank value to 0

I have Visual Composer chart which was mapped from a BI query. The row has the week # and the 7 columns are 7 quarters' sales amounts. Our goal is to show the sales amount by week. For some of the weeks, there is no sales. The problem is VC interprets blank value as 0 so the some times data lines ended at 0. Is there a way to make VC interpret blank as blank so it does not draw 0 in the chart?

Thanks,

Sharon