save individual excel files, in one workbook

[ralphtrent]

Hello
I have multiple excel files that contain a single worksheet. I would like to save them all in one workbook. The code I have put together does add a blank worksheet to the workbook, but not the worksheet from the excel doc I am telling it to grab from. Here is my code.

 private void btnMergeOutputFiles_Click(object sender, EventArgs e)
        {
            string sMergedFileName = txtOutputFolder.Text + "\\MergedFiles.xls";
            int i = 0;
            while (System.IO.File.Exists(sMergedFileName))
            {
                i++;
                sMergedFileName = txtOutputFolder.Text + "\\MergedFiles" + i.ToString().PadLeft(3, '0') + ".xls";
            }

            Microsoft.Office.Interop.Excel.ApplicationClass exApp = new Microsoft.Office.Interop.Excel.ApplicationClass();
            Microsoft.Office.Interop.Excel.Workbook exMergedWorkBook = exApp.Workbooks.Add(System.Reflection.Missing.Value);
            try
            {
              foreach (object objOutputFile in lbOutputFiles.Items)
              {
                   Microsoft.Office.Interop.Excel.Workbook exWorkBook = exApp.Workbooks._Open(objOutputFile.ToString(), Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
                   try
                   {
                       Microsoft.Office.Interop.Excel.Worksheet exWS = (Microsoft.Office.Interop.Excel.Worksheet)exWorkBook.Sheets[1];
                       exMergedWorkBook.Sheets.Copy(exWS, Type.Missing);
                   }
                   catch
                   {
                       throw;
                   }
                   finally
                   {
                       exWorkBook.Close(false, null, null);
                       exWorkBook = null;
                   }
                }
                exMergedWorkBook.SaveAs(sMergedFileName, Type.Missing, "", "", Type.Missing, Type.Missing, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
            }
            catch (Exception ex)
            {
                Common.DisplayException(ex, this);
            }
            finally
            {
                exMergedWorkBook.Close(null, null, null);
                exMergedWorkBook = null;
                exApp = null;
                lbOutputFiles.Items.Add(sMergedFileName);
            }
        }

Any help is appreciated.