What are the problems you are having with your pie chart? Using the latest build I'm not running into any problems using filtered data for the charts. Do you have a link to the page with the chart on it?
When you are creating a pie chart the x is the label and the y is the data. For the example static info the days of the week are the x and the values represented in the chart are the y. Please post back with some more info about the troubles you are experiencing and what you are trying to accomplish.