I am using Gembox to create a project where i will be adding some data to a pie chart and create ppt out of it in c#. In the documentation they have not provided any sample for pie chart but they have provided for bar chart based on which I have created a code but getting some error can anyone please help me on this topci

 using GemBox.Presentation;
 using spreedsheetCharts =  GemBox.Spreadsheet.Charts;
 using spreedsheet =  GemBox.Spreadsheet;

 // Add new PowerPoint presentation slide.
 // If using the Professional version, put your GemBox.Presentation serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY");

// If using the Professional version, put your GemBox.Spreadsheet serial key below.
SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY");

    var firstLastSlidesPresentation= new PresentationDocument();

    var slide = firstLastSlidesPresentation.Slides.AddNew(SlideLayoutType.Custom);

    // Add simple PowerPoint presentation title.
    var textBox = slide.Content.AddTextBox(ShapeGeometryType.Rectangle,
        116.8, 20, 105, 10, GemBox.Presentation.LengthUnit.Millimeter);

    textBox.AddParagraph().AddRun("New presentation with chart element.");

    // Create PowerPoint chart and add it to slide.
    var chart = slide.Content.AddChart(GemBox.Presentation.ChartType.Bar,
        49.3, 40, 240, 120, GemBox.Presentation.LengthUnit.Millimeter);

    // Get underlying Excel chart.
    spreedsheetCharts.ExcelChart excelChart = (spreedsheetCharts.ExcelChart)chart.ExcelChart;
    spreedsheet.ExcelWorksheet worksheet = excelChart.Worksheet;

    // Add data for Excel chart.
    worksheet.Cells["A1"].Value = "Name";
    worksheet.Cells["A2"].Value = "John Doe";
    worksheet.Cells["A3"].Value = "Fred Nurk";
    worksheet.Cells["A4"].Value = "Hans Meier";
    worksheet.Cells["A5"].Value = "Ivan Horvat";

    worksheet.Cells["B1"].Value = "Salary";
    worksheet.Cells["B2"].Value = 3600;
    worksheet.Cells["B3"].Value = 2580;
    worksheet.Cells["B4"].Value = 3200;
    worksheet.Cells["B5"].Value = 4100;

    // Select data.
    excelChart.SelectData(worksheet.Cells.GetSubrange("A1:B5"), true);
    
    firstLastSlidesPresentation.save("somename.pptx")

error –

‘ExcelChart’ does not contain a definition for ‘Worksheet’ and no accessible extension method ‘Worksheet’ accepting a first argument of type ‘ExcelChart’ could be found (are you missing a using directive or an assembly reference?)

I tried to find many places where i can get a code for this issue but there is no solution and also the gembox documentation is not clear on this the code i used is almost identical to the bar chart.