var wsPivot = package.Workbook.Worksheets.Add("Pivot");
                    var pivotTable = wsPivot.PivotTables.Add(wsPivot.Cells["A55"], dataRange, "Table");
                    pivotTable.MultipleFieldFilters = true;
                    pivotTable.RowGrandTotals = true;
                    pivotTable.ColumGrandTotals = true;
                    pivotTable.Compact = true;
                    pivotTable.CompactData = true;
                    pivotTable.GridDropZones = false;
                    pivotTable.Outline = false;
                    pivotTable.OutlineData = false;
                    pivotTable.ShowError = true;
                    pivotTable.ErrorCaption = "[error]";
                    pivotTable.ShowHeaders = true;
                    pivotTable.UseAutoFormatting = true;
                    pivotTable.ApplyWidthHeightFormats = true;
                    pivotTable.ShowDrill = true;
                    pivotTable.FirstDataCol = 3;
                    pivotTable.RowHeaderCaption = "Caption";

                    var pageField = pivotTable.Fields["field1"];
                    pivotTable.PageFields.Add(pageField);

                    var rowField = pivotTable.Fields["cust"];
                    pivotTable.RowFields.Add(rowField);

                    var dataField = pivotTable.Fields["id"];

                    dataField.SubTotalFunctions = OfficeOpenXml.Table.PivotTable.eSubTotalFunctions.Count;
                    pivotTable.DataFields.Add(dataField);

pivotTable.DataFields.Add(dataField);
pivotTable.DataFields[0].Function = DataFieldFunctions.Count;

Dim Field As ExcelPivotTableField = pivotTable.Fields(strFieldName)
    Dim DataField As ExcelPivotTableDataField = pivotTable.DataFields.Add(Field)
    DataField.Function = DataFieldFunctions.Sum