使用Workbooks.Open读取excel文件时出错，SOS
。。。。。。
Excel.ApplicationClass app = new Excel.ApplicationClass();
Excel.WorkbookClass workBook = (Excel.WorkbookClass)app.Workbooks(Path,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value);

报如下错误：
An unhandled exception of type 'System.Runtime.InteropServices.COMException ' occurred in excel2txt.exe

Additional information: Old format or invalid type library.

请问是怎么回事啊，编译没错的阿



[解决办法]
加这个

_Application xlApp = null;
_Workbook xlWorkbook = null;
_Worksheet xlWorksheet = null;
System.Reflection.Missing oMissing = System.Reflection.Missing.Value;