我用C#在Excel中画了一个矩形，可无法把它修改为想要的颜色？

Question

代码如下：Microsoft.Office.Interop.Excel.Application excel = new Microsoft.Office.Interop.Excel.ApplicationClass();
excel.DefaultFilePath = System.Windows.Forms.Application.StartupPath + @"\file";
Microsoft.Office.Interop.Excel.Workbook workbook = excel.Workbooks.Add(Type.Missing);Microsoft.Office.Interop.Excel.Sheets sheet = workbook.Worksheets;
Microsoft.Office.Interop.Excel.Worksheet worksheet = (Microsoft.Office.Interop.Excel.Worksheet)sheet.get_Item(1);
Microsoft.Office.Interop.Excel.Shape orgChart = worksheet.Shapes.AddShape(Microsoft.Office.Core.MsoAutoShapeType.msoShapeRectangle, 100, 100, 100, 100);
orgChart.Line.Weight = 1;
Microsoft.Office.Interop.Excel.ColorFormat color = orgChart.Fill.ForeColor;
color.RGB = 255255255;
//RGB为255255255是白色，可执行结果却为黄色
Microsoft.Office.Interop.Excel.XlFileFormat Version = Microsoft.Office.Interop.Excel.XlFileFormat.xlExcel8;
Microsoft.Office.Interop.Excel.XlSaveAsAccessMode Mode = Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange;workbook.SaveAs("dd.xls", Version, System.Type.Missing, Type.Missing, false, false, Mode, Type.Missing, Type.Missing, Type.Missing,
                Type.Missing, Type.Missing);workbook.Close(false, Type.Missing, Type.Missing);
excel.Quit();
GC.Collect();