keynote chart data not accurate

I'm trying to create a pie chart shooing profit margin. I want to illustrate that on a $100 sale, we profit $50. I open the "edit chart data" and type 50 into the first cell, and 100 into the second cell. The chart is labeled properly (i.e. $50 on one wedge and $100 on the other) but the actual visual pie portion of the chart isn't right. it's only filled up like 33% of the way instead of 50%. Why isn't it half and half!? I've changed the values from percentages to currency and I can't get it to work. I know it's something silly, please help!