I'm using version 2012.3.1310.40
I use ChartView to create a pie chart with the following data
Assets          2248550.22
Income             19748.67
Equity           2228253.95
Liability                 547.60

So, when the chart displays, the Percentage is set as follows:
Assets       50%
Income        0%
Equity         50%
Liability        0%

I notice when the percentage is 0% for any data, the pie chart shows "0%" near the chart title (please see attachment).  Or if the calculated data returns 0, it doesn't show any percentage on the chart, but it will shows "NaN" near the title as well. (please see attachment).