Pie chart and percent data label

Hello all.
I have a pie chart that simply displays total number of items and number of remaining items. I have the percentages manually calculated but wanted the pie chart to also display the percentages. The problem is that when I select Format Data Series, Data Labels, Percentage...the percent displayed on the chart is incorrect. For example, I set up a test chart with 100 total items with 50 items remaining. The calculated percentage is 50% but the pie chart is displaying 33.33% which is obviously incorrect. Anyone know how to correct the pie chart percentages?

Thanks,
Andrew