为什么我在使用xlDialogPrint.show方法时，在C＃中显示Dialog类的方法失败？

我想在C＃中使用Visual Studio打印Microsoft Excel文档，每次我尝试执行这段代码时，我都会得到Dialog类的Show方法失败exception：

bool userDidntCancel = ExcelApp.Dialogs[Excel.XlBuiltInDialog.xlDialogPrint].Show( Type.Missing, Type.Missing, Type.Missing, Type.Missing,Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing); 

这里是我正在使用的完整代码：

  Excel.Application ExcelApp = new Excel.Application(); Excel.Workbook wb = ExcelApp.Workbooks.Open( PATH, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing); Excel.Worksheet ws = (Excel.Worksheet)wb.Worksheets[1]; try { bool userDidntCancel = ExcelApp.Dialogs[Excel.XlBuiltInDialog.xlDialogPrint].Show( Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing); } catch { ExcelApp.Quit(); File.Delete("Container Status.xls"); } 

有什么我失踪？