c#打开excel出现的有关问题，哪位大侠帮解决上？（上面是代码）

c#打开excel出现的问题，哪位大侠帮解决下？（下面是代码）
OpenFileDialog dlg = new OpenFileDialog();
  dlg.Filter = "Shape地图文件(*.xlsx)|*.xlsx|全部文件(*.*)|*.*";
  dlg.Title = "打开Shape地图文件";
  dlg.Multiselect = true;
  dlg.ShowDialog();
  string[] files = dlg.FileNames;
  foreach (string file in files)
  {
  int index1 = file.LastIndexOf("\\");
  //string filepath = file.Substring(0, index1);
  string filename = file.Substring(index1 + 1);
   
  Microsoft.Office.Interop.Excel.Application excel1 = new Microsoft.Office.Interop.Excel.Application();
  listBox1.Items.Add(filepath);
  listBox1.Items.Add(filename);

  object missing= System.Reflection.Missing.Value;



  Microsoft.Office.Interop.Excel.Workbook book1 = excel1.Application.Workbooks.Open(filename, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing);（这条语句报的错）


  book1.SaveAs("D:\\text.xlsx", Microsoft.Office.Interop.Excel.XlFileFormat.xlOpenXMLWorkbook, Type.Missing, Type.Missing, false, false, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange, Microsoft.Office.Interop.Excel.XlSaveConflictResolution.xlLocalSessionChanges, Type.Missing, Type.Missing, Type.Missing, Type.Missing);


  excel1.Quit();
  }


错误信息：

[解决办法]
excel1.Application.Workbooks.Open(filename)试试看。我记得后面参数不写也行。
[解决办法]
missing默认个数查下！
[解决办法]
string filename = file.Substring(index1 + 1);
Microsoft.Office.Interop.Excel.Workbook book1 = excel1.Application.Workbooks.Open(filename............
这个filename是不是没有路径只有文件名？参数换成file看看。