title: Excel Returns Null After Line 144 using C# Microsoft Interop Excel
body: <p>In C#, I've opened an Excel spreadsheet and I am iterating through it.  Whenever I get to line 144, the spreadsheet value returns null for every single line following it.  Looking at the spreadsheet, it is clearly not null for lines 144 - 250.  I tried saving it in different versions but that didn't work.  I've tried copying and pasting into a brand new worksheet.  Nothing has worked. Here is my code:</p>
  
  <pre><code>        // initiate Excel
          Excel.Application xlApp;
          Excel.Workbook xlWorkBook;
          Excel.Worksheet xlWorkSheet;
          object misValue = System.Reflection.Missing.Value;
  
          xlApp = new Excel.Application();
          xlWorkBook = xlApp.Workbooks.Open(lblFileName.Text, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
          xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
  
          //Get the used Range
          Excel.Range usedRange = xlWorkSheet.UsedRange;
  
          //Iterate the rows in the used range
          string customerNumber;
          string amount;
          int i = 0;
          decimal dAmount = 0;
  
          bool runProcess = true;
          bool hasHeader = false;
          string cellValue;
          foreach (Excel.Range row in usedRange.Rows)
          {
              i++; 
              // Column 1 is customer number
              // THE FOLLOWING LINE RETURNS NULL STARTING AT ROW 144
              cellValue = row.Cells[i, 1].Value2 == null ? "" : row.Cells[i, 1].Value2.ToString();
              if (!(cellValue.Length &gt;= 5 &amp;&amp; cellValue.Length &lt;= 20))
              {
                      MessageBox.Show(cellValue + " Must be between 5 and 20 Characters - File Will Not Be Processed Row#" + i.ToString());
                      runProcess = false;
              }
  
          }
          // run process
          // release EXCEL
  </code></pre>
  
  <p>I did try  row.Cells[i, 1].Value2,  row.Cells[i, 1].Value and  row.Cells[i, 1].Text and got the same results for all.  I am including "using Excel = Microsoft.Office.Interop.Excel;" </p>
  
  <p>Sample Data from Excel</p>
  
  <pre><code> 4492605768531895  15.95
   4492605768536544  19.95
   4492605768565459  11.95
   4492605739542347  14.95
   4492605768635795  25.95
  </code></pre>