Pie chart from collection parameter

[dgiulian]

Hello,

I need to do a Pie chart using labels and values contained in a collection that is passed as a parameter, but I dont know how to do it.

In the chart data, within the details tab, i've put $P{labels}  in the label expresion field and $P{values} in the value expresion field ( labels and values are the names of the collections) but when i try to preview the report I get the following error message:

Error filling print... Error evaluating expression:

Source text: $P{values}