New Post: Issue with Pivot Tables

I am unable to create a Pivot table with ReportFilters. Once I add a report filter, I get an error trying to open the excel file. To reproduce, I used the Pivot example from the site. The only change I made was changing "Month" from a column to a report filter. The code is below:
Can you tell me if I am doing anything wrong?

      var pastries = new List<Pastry>
        {
           new Pastry("Croissant", 150, "Apr"),
            new Pastry("Croissant", 250, "May"),
            new Pastry("Croissant", 134, "June"),
            new Pastry("Doughnut", 250, "Apr"),
            new Pastry("Doughnut", 225, "May"),
            new Pastry("Doughnut", 210, "June"),
            new Pastry("Bearclaw", 134, "Apr"),
            new Pastry("Bearclaw", 184, "May"),
            new Pastry("Bearclaw", 124, "June"),
            new Pastry("Danish", 394, "Apr"),
            new Pastry("Danish", 190, "May"),
            new Pastry("Danish", 221, "June"),
            new Pastry("Scone", 135, "Apr"),
            new Pastry("Scone", 122, "May"),
            new Pastry("Scone", 243, "June")
        };


        var workbook = new XLWorkbook();
        var sheet = workbook.Worksheets.Add("PastrySalesData");

        // Insert our list of pastry data into the "PastrySalesData" sheet at cell 1,1
        var source = sheet.Cell(1, 1).InsertTable(pastries, "PastrySalesData", true);

        // Create a range that includes our table, including the header row
        var range = source.DataRange;
        var header = sheet.Range(1, 1, 1, 3);
        var dataRange = sheet.Range(header.FirstCell(), range.LastCell());

        // Add a new sheet for our pivot table
        var ptSheet = workbook.Worksheets.Add("PivotTable");

        // Create the pivot table, using the data from the "PastrySalesData" table
        var pt = ptSheet.PivotTables.AddNew("PivotTable", ptSheet.Cell(1, 1), dataRange);

        // The rows in our pivot table will be the names of the pastries
        pt.RowLabels.Add("Name");

        // The columns will be the months
        pt.ReportFilters.Add("Month");

        // The values in our table will come from the "NumberOfOrders" field
        // The default calculation setting is a total of each row/column
        pt.Values.Add("NumberOfOrders");


        workbook.SaveAs("c:\\temp\\PastrySample.xlsx");