getSeries() does not work in Excel scripts

Question

Hi,

I got an issue with using the getSeries() function in excel script.

I want to write script to change the color of the pie chart. I did it manually and I recorded it.

The below is the code:

function main(workbook: ExcelScript.Workbook) {
let selectedSheet = workbook.getActiveWorksheet();
let TestingChart = selectedSheet.getChart("TestingChart");
// Set fill color on series for a chart
TestingChart.getSeries()[0].getFormat().getFill().setSolidColor("#FF0000");
}

However, when I try to run it again. I got error "Chart getSeries: The requested resource doesn't exist."

the chart is a pie chart and I am pretty sure the chart contains some series on it.

Thank you.