Excel file is not saving in correct path

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C#

I'm using the following c# code to save an excel file in the application start-up path folder. But it's saving in 'My Documents' Folder. Can someone please explain?
Thank you

string dailyFile = "DeliveryChallan(" + date + time + ").xls";

File.Copy(Application.StartupPath + "\\DCTemplate.xls", 
    Application.StartupPath + dailyFile);

Microsoft.Office.Interop.Excel.Application xlApp;
Microsoft.Office.Interop.Excel.Workbook xlWorkBook;
Microsoft.Office.Interop.Excel.Worksheet xlWorkSheet;

object misValue = System.Reflection.Missing.Value;
xlApp = new Excel.ApplicationClass();
xlWorkBook = App.Workbooks.Open(Application.StartupPath + dailyFile,
    misValue, misValue, misValue, misValue, misValue, 
    misValue, misValue, misValue, misValue, misValue, 
    misValue, misValue, misValue, misValue);
xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

xlWorkBook.Save();
xlApp.Workbooks.Close();
xlApp.Quit();